The purpose of this study is to clarify the best habitable conditions for marine organisms in a tide pool. From this view point, field observations on marine organisms andtheir life environment are conducted in the tide pools located at the both natural lagoonand man-made one.
It is found that the number of species of marine organisms in the tide pools located at natural lagoon is larger than that at man-made one. This depends on the roughness of side and bottom, the water depth and total volume of boulders scattered in the tide pool.