Recent studies of decapod crustaceans in anchialine and submarine caves of the Ryukyu Islands were reviewed. A total of 10 species, belonging to 7 genera of 5 families, have been recorded in anchialine caves, and all of them are listed on the Red List (List of Endangered and Threatened Species in Japan or Okinawa Prefecture). In the submarine caves, remarkable findings of decapods and other crustaceans are continuing even in recent years. Further “many eyes” will be poured into the submarine caves, it is expected that the characteristics of the animal communities in the Ryukyu Islands will be understood in more detail.