Yachts and marinas as hotspots of coastal risk 1

: Despite being exceptional concentrations of valuable economic assets, yachts and marinas are typically overlooked in the geography of coastal risk. Focusing on the Mediterranean, which hosts the majority of the world ’ s yacht activity, we examine three decades of yacht insurance claims in the context of natural hazards and marina development. We find indications that yachts and marinas manifest the same generic relationships between exposure, hazard, and vulnerability observed in terrestrial coastal-risk systems. Given the fundamental importance of yachts and marinas to nautical tourism and strategies for “ Blue Economy ” growth, particularly in Europe, the role of yachts and marinas in the dynamics of coastal risk must be better understood — but any such insight will first require standardised, comprehensive datasets of yacht movements and marina infrastructure.


Introduction
Research into coastal risk tends to stand with its back to the ocean. Risk can be framed as a compound function of hazard, exposure, and vulnerability (Crichton 1999;NRC 2014). Coastal hazards push landward in the form of storm events, sea-level rise, flooding, and chronic erosion. Exposure of physical assets to these hazards is measured by economic valuation of shorefront development and infrastructure. Vulnerability is typically defined as the "susceptibility" of an asset to damage (NRC 2014;IPCC 2014), and can be represented by the presence and (or) integrity of a mitigating buffer between hazard and exposure: engineering works like sea walls or beach nourishment, for example, built to protect coastal development from environmental forces (Armstrong et al. 2016;Lazarus 2019a, 2019b).
By contrast, few studies of coastal geography stand on the shore and look out to sea (Steinberg 1999(Steinberg , 2001. Fewer still face the sea but focus on the foreground, to consider the stands of masts and rigging and cabin superstructures that rise from harbour quays all over the world (Kizielewicz and Lukovic 2013;Lukovic 2013). Marinas, and the yachts within them, constitute hotspots of exposure to coastal hazard-concentrations of high-value economic assets densely packed behind concrete breakwaters. Yet they are notably absent from critical examinations of coastal risk.
Here, we suggest that marinas and yachts reflect the same dynamics of risk that are more typically associated with coastal real estate, and therefore warrant the same kind of analytical scrutiny. Focusing on the Mediterranean Sea, where the majority of the world's yacht activity takes place (European Commission 2016a, 2016b), we explore a dataset of over 19 000 insurance claims filed for yachts in the Mediterranean between 1987 and 2017. We supplement those data with contextual evidence of coastal hazards in the Mediterranean Sea, along with trends in Mediterranean marinas and global production of superyachts >30 m in length. We offer that marinas and yachts represent an unexplored domain of coastal risk, with vital economic implications for nations-and multi-national regions-that have become dependent on revenue from tourism and service sectors.

Marinas are not ports
In academic literature, topics related to commercial ports exist in a mixed-disciplinary space between engineering and business management. A broad swath of research into ports may include or apply indirectly to marinas because both contend with the same issues of basic operation (Nursey-Bray et al. 2013;Asariotis et al. 2018;de Langen et al. 2018): maintenance of navigational access; efficiency of use; maximum allowable vessel size, and strategies to allow ever larger maxima. Work at the interface of oceanography and coastal engineering applies climate-change scenarios and hydrodynamic modelling to explore the physical impacts of sea-level rise, storm surge, and wave attack on port infrastructure (Casas-Prat and Sierra Pedrico 2010;Nursey-Bray et al. 2013;Androulidakis et al. 2015;Chhetri et al. 2015;Sierra Pedrico et al. 2015;Sánchez-Arcilla et al. 2011Christodoulou et al. 2019). A deep literature examines environmental impacts of port operations, and efforts to regulate them (Peris-Mora et al. 2005;Davenport and Davenport 2006;Darbra et al. 2009;Petrosillo et al. 2009;Ng and Song 2010;Di Franco et al. 2011;Gómez et al. 2017).
Relative to ports, marinas and the boats they host receive little formal academic attention. (Instead, they sustain a sub-industry of glossy trade and marketing publications.) Where ports host all types of vessels, marinas cater to private pleasure craft (Piccinno and Zanini 2010;Lukovic 2013). That difference is more than a technicality: if the principal function of a port is shipping or commercial trade (such as a fishing fleet), then the principle function of a marina is hospitality. A marina might provide the bare essentials, such as fuel and fresh water, or it may offer clientele an integrated onshore complex of luxury amenities, including hotel suites, dining, and shopping, literally above and beyond its utilitarian services for vessel repair, maintenance, and provisioning (European Commission 2016b). A marina is sometimes characterised as a hotel to which guests bring their own suite (Honey 2018). A less glamourous analogy is a floating RV park. So when marinas do appear in academic analyses, they are the denizens of tourism and leisure studies, in which typical concerns include opportunities for market growth and the benefits of competitive optimisation (Oehmichen and Bourdais 2007;Raviv et al. 2009;Vlasic et al. 2019). Yacht design and construction are scientific processes (Larsson 1990;Lazarus 1999Lazarus , 2007Lazarus , 2012Eliasson et al. 2014) that involve complex hydrodynamic modelling (Milgram 1998;Lombardi et al. 2012;Blount 2014;Dawson 2015), physical experiments in towing tanks (Fossati et al. 2015), and production techniques at the frontier of materials science (Lazarus 1997(Lazarus , 2015Baley et al. 2015;Cucinotta et al. 2017). However, upon completion, yachts as subjects of academic research shift from being showcases of maritime industry to trophies of the marinas they frequent.
Nautical tourism is a nascent academic field that focuses on the marina, charter, and cruise industries (Lukovic 2013), and is a branch of maritime tourism-the "water-based" counterpart to "land-based" field of coastal tourism (Hall 2001;Agarwal 1997Agarwal , 2002Jennings 2004;ECORYS 2013). During the past decade, in Europe, nautical tourism has ridden a wave of interest in the "Blue Economy" as an emerging source of potential economic growth (ECORYS 2012;European Commission 2016a, 2016b. Between 2006 and 2011, the gross value added from yachting and marinas increased by approximately 37%, from an estimated €28 billion to €39 billion (ECORYS 2013). Employment in the sector increased 29% over the same period, from 291 000 to 372 000 jobs-and it is unclear whether these figures even account for the yacht-charter market (ECORYS 2013). In 2014, "the nautical sector"including specialised services such as "boat repairs and services, boat and watersports charter/rental, sailing schools, boat dealers/brokers, chandleries, marinas, and financial and other professional services"-posted an estimated annual turnover between €20 billion and €28 billion (European Commission 2016a). Marinas alone may deliver 14%-20% (€4 billion) of that turnover (ECORYS 2015). By any measure, marinas are big businessand indivisible from their clientele.

Consider the yacht
Not every vessel in a marina is a yacht, but yachts are the symbionts of the marina industry. Although there is no formal definition for what makes a vessel a yacht, most descriptions emphasise that a yacht is for pleasure and recreation (Piccinno and Zanini 2010), defined more by their culture of use than by technical specifications. Yachts are the economic lifeblood of nautical tourism because of charter hire. The beating heart of the global charter market is in Europe, where the yacht-charter industry posts annual turnover figures of €6 billion (ECORYS 2015).
Yachts 24 m or longer, termed superyachts, comprise a tiny fraction of the recreational boating fleet-around 0.1% of all recreational boats in Europe (European Commission 2016a)-but marinas compete for their patronage (Gorman 2015;Mathieson 2016;European Commission 2016b). Twenty-four metres is an arbitrary threshold, except that special regulations and "large vessel" safety codes come into effect at that length overall (Lorenzon and Coles 2012;Paolo Moretti 2015). Industry trackers like Superyacht News and Superyacht Times tend to follow vessels >30 m. In 2019, the global fleet of superyachts >30 m in length was estimated at 5096 vessels (Fig. 1a). Deliveries of completed superyachts >30 m dropped after the 2008 financial crisis but has been stable, if reduced from its pre-crash high, for nearly a decade. The annual "casualty rate" of the global superyacht fleet is low: one trade source counted only 158 superyachts >30 m lost since 1980, a total that includes projects under construction (Fig. 1a, inset), or loss a rate of ∼0.1% of all superyachts per year. Yachts >40 m have accounted for a comparatively larger proportion of yacht deliveries since 2009, including an increasing number of yachts >80 m (Fig. 1b). The largest vessels are large enough to skew metrics like mean superyacht length through time (Fig. 1c), when median length might more accurately describe the fleet (Jackson 2019).
Nevertheless, as the size and number of superyachts increase (Fig. 1), so does demand for services to accommodate them (European Commission 2016b). In Europe, prospects for economic growth effectively assume that the total number of marinas has saturated but that berths in a marina can be reorganised, at least within the physical constraints of harbour geography (de Swart et al. 2018;European Commission 2016b). The emerging business opportunities are therefore in the upgraded services and amenities that marinas may provide (ECORYS 2015), alongside improved coastal defences to better protect the assets of nautical tourism from climate-driven hazards (de Swart et al. 2018).

The breakwater effect
In terrestrial settings, the promise of asset protection is the key driver of a feedback known as the safe-development paradox or the levee effect (Burby 2006;Di Baldassarre et al. 2013a, 2013b, such that investment in hazard protection may have the unintended consequence of stimulating further development behind that protection. This dynamic echoes Jevons' paradox (Jevons 1865;Alcott 2005;Sorrell 2009;Armstrong et al. 2016), a counterintuitive theory in environmental economics named after the English economist William Stanley Jevons, who argued that more efficient steam engines drove more coal consumption, not less (Jevons 1865). Reframed in terms of coastal risk, investment in "better" protection from coastal hazard may stoke more intensive development of coastal real estate, which in turn will demand further investment in protection (Armstrong et al. 2016).
Here, rather than houses popping up on nourished beachfronts or leveed floodplains (Di Baldassarre et al. 2013a, 2013bArmstrong et al. 2016;Armstrong and Lazarus 2019a), yachts tie up behind marina breakwaters. Higher-value assets demand bespoke accommodation-super-berths for superyachts-and additional protection. Although hazard intensification like sea-level rise and storminess can drive increased coastal risk, so can a feedback between exposure and vulnerability-even in the absence of any change in hazard (Criss and Shock 2001;Werner and McNamara 2007;Lazarus 2014). If marinas build for the yachts they want rather than the yachts they have (Raviv et al. 2009;ECORYS 2015;Gorman 2015;Mathieson 2016), then the risk feedback between assets and protection, between exposure and vulnerability, ratchets forward.

Analysis: The Mediterranean case
To explore signatures of risk feedbacks in the yachting sector, we look to the Mediterranean. Half of the gross value added and employment totals for the nautical sector  Tables S1 and S2 2 . spring from the Mediterranean, along with an estimated 40% of the global charter-boat market (European Commission 2016a). In 2011, an industry analysis reported that 60% of the world's superyachts are based in the Mediterranean (European Commission 2016b), with 217 of 401 "high-quality" marinas capable of receiving vessels >24 m long (ECORYS 2013; European Commission 2016b). In 2017, Superyacht News reported that 75% of the global superyacht fleet is in the Mediterranean during the northern-hemisphere summer (and 56% in the winter), creating a seasonal bottleneck in which the number of vessels >30 m cruising the summer Mediterranean exceeds the number of available berths in the entire region by ∼15% (3796 superyachts to 3287 superyacht berths) (Mathieson 2017). A marina berth (or "slip" in US parlance) is a designated place to secure a vessel-like a parking space-and typically implies dock access (as opposed to a mooring or anchorage, situated out in the harbour and thus requiring a tender to get ashore). Competition for superyacht berths has prompted the suggestion that berth ownership become the new economic model for marinas, with berth subletting as a new investment frontier (Redmayne 2016). Even the European Commission, in its 2016 assessment of nautical tourism in Europe, notes that "while the number of superyacht berths is increasing : : : , the number of berths in the most popular cruising zones : : : lag behind demand" (European Commission 2016a). These conditions make superyachts the indicator species of nautical tourism, and the Mediterranean the epicentre of coastal-risk dynamics arising from marinas and yachts.

Three decades of yacht insurance claims
From Pantaenius Yacht Insurance, Europe's largest insurer of yachts, we obtained a record of over 19 000 yacht insurance claims filed with the company from the Mediterranean between 1987 and 2017. Each entry shows the date, the amount of the claim, and if the claim is associated with a storm event. Most claims noted the country in which the incident occurred, but spatial locations of claims (Fig. 2) are listed separately (divorced from their corresponding records) and not necessarily precise. The entries are otherwise anonymised, with no information about the client or the technical specifications of the yacht.
The most striking trend is the explosive increase in the total number (Fig. 3a) and total value of claims (Fig. 3b) over time, especially since 2000. Half the total number and half the total value of claims in the Pantaenius records are filed after 2010 ( Fig. 3; Table S3 2 ). However, the relative proportion of storm claims, both in number and associated value, has remained effectively stable in the past 20 years, as has the proportion of "zero claims"-a claim below the policy deductible-related and unrelated to storm events (Figs. 3 and 4a). Claim counts reflect a pattern of seasonality, with more storm claims filed during the broad months of the Mediterranean winter, and most non-storm claims in the summer peak of July and August (Fig. 4b). Apart from growth in the sheer number of claims, the distribution profile of claim values appears to have changed little over time (Fig. 4c). This stability is also reflected in median claim value over time (Fig. 4d), which has been effectively flat since the 1990s for storms and non-storms alike (Figs. 4e and 4f). Mean claim values are more influenced by large outliers (Figs. 4d-4f), and their time series reflects a subtle drift in the claim values towards distributions with heavier tails at the high end of the range (Fig. 4c).

A hazardous coast
The lack of disproportionality in storm-related claims over the past three decades is an intriguing result in the context of coastal risk. The Mediterranean is not exempt from coastal hazard. "Medicanes"-a contraction of "Mediterranean hurricanes"-are intense  and unrelated (dark gray) to storm events. All claim values in our analysis are adjusted to 2012€. Black line tracks total value of claims per year. Inset shows relative proportion of storm-related and non-storm-related claim values over time. Although the number and value of storm-related claims has increased in the past two decades, the number and value of storm-related claims has not increased disproportionately relative to claims unrelated to storm events. For data, see Tables S3 and S4 2 . cyclonic windstorms that for all meteorological intents and purposes look and behave like tropical cyclones (Romero and Emanuel 2013;Cavicchia et al. 2014a). Modelling suggests that under future climate change medicanes may occur less frequently, but the number of violent storms may increase (Romero and Emanuel 2013;Cavicchia et al. 2014b) along with the magnitudes of storm surges in select Mediterranean subregions (Androulidakis et al. 2015). Analysis of the incident wave climate for the Catalan coast of Spain suggests a trend towards more storm waves from the south-problematic because most Catalan harbour entrances, by design, are open to the southwest to provide shelter from prevailing storms out of the northeast and east (Casas-Prat and Sierra Pedrico 2010). Modelling of climate-driven changes in wave agitation for harbours along the northwestern Mediterranean suggests that future agitation may increase during the summer months, when harbours are busiest (Sierra Pedirco et al. 2015). Even if storm intensity were to remain constant into the future, onshore impacts of Mediterranean storms, medicanes  Fig. 3b inset). The spike in 2007 comes from a single claim for nearly €1.7 million. The relative stationarity of the time series suggests no disproportionate increase in storm damage in the Mediterranean in the past three decades. (b) Claim types (related and unrelated to storms) by month of occurrence, as a percentage of the total number of claims in the dataset. More storm-related claims occur during the Mediterranean winter months. (c) Distribution of all claim values per year, with claim value plotted on a log-scale. Gradient in line colour from dark to light tracks with time; decadal years are denoted in bold. Dominant pattern is the growth in number of claims, with a more subtle shift towards higher mean values. Normalising by the total number of claims each year (inset) shows relatively little change in the distribution shape over three decades. (d) Although mean claim value has increased over time, median claim value has not, illustrating the sensitivity of the mean to a small number of especially high-value claims. (e) With the exception of 2007, neither the mean nor median value of storm-related claims has increased notably since the 1990s. (f) The upward drift in mean claim value overall (panel d) appears to be driven by claims unrelated to storm events. Median claim value for non-storm claims has remained effectively constant for 20 years. For data, see Tables S5 and S6 2 . and otherwise, will likely increase regardless as a result of regional sea-level rise (Sánchez-Arcilla et al. 2011. If wave agitation is one issue-a heaving marina is a dangerous marina-then breakwater and seawall integrity is another. The Ligurian coast of northeastern Italy is in one of the Mediterranean zones of "extreme wind tracks" (Nissen et al. 2010). During a "superstorm" in October, 2014, the Ligurian port town of Rapallo saw its breakwater collapse, releasing a surge of water and heavy waves into the harbour that swamped half of the approximately 400 vessels in the Carlo Riva Marina (McCabe 2018;Overton 2018;Superyacht Investor 2018). A representative of Pantaenius interviewed after the event estimated that damage to superyachts in the marina might top €75 million (Superyacht Investor 2018). Moreover, the breakwater at Rapallo had collapsed before, in November, 2000, when a "freak wave" wreaked similar havoc (Overton 2018;Superyacht Investor 2018). The marina had responded by raising the top of the new breakwater by 1.3 m, bringing the rebuilt height to 6.5 m-"But not enough with this exceptional event," the marina director said after the recurrence (Overton 2018).
In the Pantaenius data, five countries-Italy, Spain, France, Croatia, and Greece, respectively-account for 91% of the total number of yacht insurance claims and 92% of their total value (Fig. 5a). But there is no indication that any one Mediterranean country in the top 10, by volume of associated claims, accounts for an outsized number of storm claims relative to non-storm claims (Fig. 5b). For example, Italy is associated with more claims (27%) than any other country in the dataset but shows a proportional number of storm (27%) and non-storm claims (26%) relative to the Mediterranean totals. If any subregional patterns of storm impacts are taking shape across the Mediterranean, they are not evident in these three decades of insurance claims.

Exposure is driving risk
We might have expected that insurance claims would be, if anything, an oversensitive metric of storminess. Industry coverage remarked on the superyacht insurance market "operating at an unsustainable loss ratio" for much of the past decade-that is, yacht Fig. 5. Insights from Mediterranean subregions. (a) Five countries-Italy, Spain, France, Croatia, and Greeceaccount for 91% of the total number of yacht insurance claims in the Pantaenius dataset and 92% of their total value (inset). (b) Plotting for each country its proportions of storm-related claims (relative to the total number of storm-related claims in the dataset overall) versus non-storm-related claims (relative to the total number of nonstorm-related claims in the dataset overall) shows that no single country accounts for a disproportionate number of storm-related claims in the Mediterranean. For data, see Tables S7 and S8 2 . insurance was relatively inexpensive-such that in 2018, insiders were anticipating a market-wide rate hike (Jackson 2018. The ballooning of yacht insurance claims since 2000 (Fig. 3) is probably the emergent result of a number of drivers. Some maritime lawyers perceive that the yacht world has become more litigious over time, with a pile-up of claims over paint work and chartering mishaps (McCabe 2014). The trend in claims might therefore reflect a change in yacht-ownership culture-and the legal intermediaries that serve it-as much as any change in yacht-market volume. But the absence of a clear storm signal still suggests that the "exposure" component of this maritime-risk system has rapidly outstripped any changes in natural hazard.
The quest for customer satisfaction may exert more influence on marina adaptation than the spectre of severe climate-driven hazards. Surveys of marina operators suggest that addressing direct, "tangible" forces like visitor numbers tend to outweigh comparatively indirect forces like climate change (Raviv et al. 2009;European Commission 2016b). The UK and Australia offer guidance on maritime industry adaptation to climate change Scott et al. 2013;MCCIP 2014), but a recent report on infrastructure in European ports conveys adaptation to climate change as an afterthought behind drivers of more immediate investment related to trade volume and fleet accommodation (de Langen et al. 2018). When adaptation actions are mentioned, traditional "hard engineering" solutions, like breakwaters, predominate (Asariotis et al. 2018) over "soft" or "green" adaptations, such as cultivated seagrass meadows to dissipate wave energy (Sierra et al 2017). An international survey of port authorities in 2009 (Becker et al. 2012) found that fewer than 10% of respondents had specific climate-change planning in place, ∼10% had climate adaptation funded as budget line-item, and ∼15% had climate change addressed in the port strategic plan. Most of the ports used a design standard of a 100-year flood event. Regarding expansion and improvement projects for the coming decade, 19% of respondents reported that they were building new storm protections-and 78% reported plans for the construction of new quays or berths.
Unfortunately, the marina sector has a data problem. The summative "Assessment of the impact on business development improvements around nautical tourism" for the European Commission laments a lack of "comprehensive information relating to the size, type and capacities of the marina industry in Europe; assessments of the direct and indirect economic impacts of marinas and boating activities across the EU; data showing the frequency of boating participation and the movements of boaters between marinas and between Member States" (European Commission 2016a). National statistics aside, even for commercial purposes like pre-booking berths for cruising yachts "there is still no comprehensive database of yacht harbours, marinas, or yacht clubs" (Siches 2016). Try to determine, as we did for this analysis, how many marinas there are in the Mediterranean, and the numbers are wildly scattershot. Estimates quoted in European Commission reports (European Commission 2016a, 2016b and in the thin academic literature that exists on nautical tourism (Lukovic 2013) come from searching listings by country in the website portbooker.com. Aggregator websites for marina bookings-and likewise cruising guidebooksare plentiful, but patchy; whether advertisement-driven or curated, they are not comprehensive listings (nor are they obligated to be). The World Port Index (NGIA 2019), compiled by the US National Geospatial-Intelligence Agency, lists "major ports and terminals" worldwide, but does not include a separate distinction for marinas (which may be included in a given port complex, or may be stand-alone entities). The International Council of Marine Industry Associations (ICOMIA) publishes an annual "global data summary" stats-book and has a "Marinas Group", but categories and responses by country vary from year to year.
The only apparently consistent, multi-annual record of marinas and berths that we found comes from Spain (FEAPDT 2016), which shows a 41% jump in the number of Mediterranean marinas and a 23% increase in the number of berths between 2003 and 2014/15 (Fig. 6a). The number and value of claims registered in Spain in the Pantaenius database climbed steeply over the same period (Fig. 6b). To the extent that we might use Spain as an index for the rest of the Mediterranean, plotting claims in Spain as a function of annual berth density (Fig. 6c)-the number of berths divided by the number of marinas-suggests that growth in claim numbers slows with corrections towards lower berth density. We might hypothesise that berth density might saturate or increase again in the future as the number of Spanish marinas reaches a geographic maximum (de Swart et al. 2018;European Commission 2016b). But if the size of the Mediterranean yacht fleet continues to grow, claims registered in Spain may increase more dramatically still. While an apparent relationship between insurance claims and berth density does not prove unequivocally a feedback between yacht exposure and marina protection, it indicates a vital link-which more specific information at the marina scale (berths, occupancy rates, attributable claims) can only clarify.

Discussion: Before the pandemic, and after
Our analysis reflects a pre-pandemic past. None of the economic forecasts for European "blue growth" consider the ramifications of a world in lockdown-a grand mal seizure in global tourism. How the direct and indirect economic shock of the COVID-19 pandemic will affect the multiple, nested industries of nautical tourism-from vessel production to marina services-is as unknown as the impact of the virus on every other globalised market. That said, we can safely assume the damage will be disproportionate. The dishwashers at luxury marinas will be harder hit than the diners. In 2008, the global financial crisis upended superyacht production (Fig. 1a); what this new global crisis will force onto production trends remains to be seen. In stark contrast to their emerging-tech clientele, marinas are notoriously slow innovators. In a 2016 assessment of the European marina sector, access to wireless internet was still listed as a leading issue (European Commission 2016b). If climate-change-proofing marina infrastructure was already a low priority, then triaging a mid-pandemic business model has made it even lower. . Claim growth appears to slow following adjustments towards lower berth density (inset). For data, see Tables S9 and S10 2 .
In a cancelled tourist season, berths of empty yachts start to resemble rows of abandoned buildings. No one is living aboard. Apart from someone who might come once a day, if that frequently, to check that the bilge pump is working, the crews are gone. If the yacht is a charter vessel, the owner is a company. For insurers, the nail-biting concern is fire. Most superyacht losses are the result of fires (Wood 2019). And while the possibility of a marina fire is worrisome, a blaze at a shipyard is worse. In September 2018, when a fire struck the Lürssen shipyard in Bremen, Germany, yacht insurers braced for an expected loss of €600 million, attributed to a 140 m project that was nearly finished (Blazeby 2018;Jackson 2018). Superyacht owners may use the empty time of the pandemic to send in their vessels for repair and refitting, but only a handful of shipyards are equipped to handle the largest superyachts. According to one marine insurance director, present circumstances make it more likely that multiple super-large superyachts will be in the same shipyard at the same time: "If you take the top ten largest superyachts in the world, it is possible for at least five or six of them to be in one of these yards at any single time. Those six boats alone could have an aggregate value of two to three billion, plus other boats in the yard, in the event of a fire" .
This scenario, in particular, illustrates how yachts-and where they reside-can represent an especially concentrated form of asset exposure in the context of coastal risk. The scenario also illustrates the scale of wealth disparity that superyachts embody. In September, 2019, Hurricane Dorian razed the Bahamas as a Category 5 storm, leaving behind an estimated USD3.4 billion in damages (IDB 2019). In a strictly by-the-numbers tally, the money parked in a handful of super-superyachts is the direct financial cost of a Caribbean hurricane.
Yachts and marinas will survive the COVID-19 pandemic-which means they will still be woven into the complicated fabric of coastal risk, as they have been for decades, even if research into coastal risk has not accounted for them. And given the magnitude of economic exposure they represent, yachts and marinas should be accounted for more deliberately. Much the way mobile phone data can reveal the mass movements of people in disaster-prone settings (Deville et al. 2014;Wilson et al. 2016), perhaps a new generation of vessel transponders will track the movements of pleasure craft and reveal spatiotemporal patterns of exposure to marine hazard events. Much as remote-sensing efforts are underway to map every building on the planet (George 2019), comparable mapping must be within reach for the world's marinas and an estimate of their berth capacities, in concert with standardised census-taking. Documenting changes in the spatial footprints of yachts and marinas over time would contribute to a growing body of research into the phenomenon of marine sprawl (Duarte et al. 2012;Dafforn et al. 2015;Firth et al. 2016;Bishop et al. 2017;Lazarus 2017). If maps of commercial shipping routes and industrial-scale fishing activity are providing a novel perspective of the global ocean, both modern and historical (Burn-Murdoch 2012; Shipmap 2016; Kroodsma et al. 2018), then yachting itineraries must likewise describe an overlapping but distinctive geographic space, a gilded network that contracts and expands, surges and slows by season-and grows and densifies by the year.

Conclusion
For all that yachts and marinas remain a largely uncharted part of marine geography (Steinberg 1999;Smith 2000), their co-dependence may drive the same systemic dynamics of risk that pertain to subdivisions on leveed floodplains or summer houses on nourished beaches (Stevens et al. 2010;Armstrong et al. 2016;Armstrong and Lazarus 2019a). Fundamentally, these settings spur the same paradoxical feedback (Burby 2006;Werner and McNamara 2007): a physical asset of significant economic value demands protection from environmental hazard; investment in engineered defences fosters a sense of safety rather than precariousness; that projection of safety indirectly attracts and encourages more-and more valuable-physical assets, which in turn demand a greater level of protection. The risk system that we describe from Mediterranean data-the epicentre yachting world, by volume of activity-is qualitatively similar anywhere marinas and yachts are found in numbers, whether elsewhere in Europe, or along the seaboards of the USA, or throughout the Caribbean, or across the western Pacific (Lukovic 2013; European Commission 2016b; Honey 2018). Future stimulus plans for blue growth and the nauticaltourism sector need to consider how those same strategies may serve to intensify coastal risk, with potentially disastrous economic consequences.