This paper discusses the diversity, common features, and geographic distribution of submarine cave bivalves collected with SCUBA from a number of islands around the Philippine Sea (Okinawa, Miyako, Yonaguni, Daito, Bonin, Bohol and Cebu of the Philippines, Palau, and Guam). Common significant characteristics of cave bivalves are: (1) unique taxonomic assemblage, (2) reduced adult size, (3) many deep-water genera (4) occurrence of several ''cavity-dwelling'' shallow-water genera on the exposed wall and sediment surface, (5) frequent paedomorphosis by progenesis, (6) relative abundance of non-planktotrophic species, (7) low fecundity and dominance of brooding, and (8) archaic life mode reminiscent of a fauna before the ''Mesozoic marine revolution'' (rarity of sedentary species and deep burrowers). These features must be related to one another and are generally regarded as due to a common adaptive strategy toward the oligotrophic condition and low predation pressure of cave habitats. It is still mysterious how cave bivalves, even brooding species, have become so extensively distributed in the western Pacific region. Although there is no positive evidence, rafting is a possible mechanism of transoceanic dispersal for minute epibyssate bivalves.