简介：Itistheyear1891andamilitarydoctor,LieutenantClaudedeRoss(ClaudioCassinelli)asurvivorofnotone,buttwoshipwrecks,washesashoreonamysterious,unchartedCaribbeanislandalongwithahandfulofconvicts.Whenseveraloftheseconvictsmeetunfortunateendsatthehandsofthetitularfishmen,Claudeandtheothersurvivorsfleeintothejungle,onlytoencounterthesadisticEdmondRackham(RichardJohnson)andhisbeautifulcaptiveAmandaMarvin(BarbaraBach). Amanda'sfather,ProfessorErnestMarvin(JosephCotten),aonce-famedbiologist,hasdiscoveredawaytotransformhumansintoamphibiouscreaturesandcontrolstheireverymove.RackhammanipulatesMarvinintoperformingtheprocedureuponbothwillingandunwillingparticipantsbyassuringhimthathisworkisundertakenforpurelyscientificandhumanitarianmotives(Marvinhopestoreducestrainontheworldfoodsupplybycreatingaraceofpeoplewhocanliveintheresource-untappedocean).HavingdiscoveredthelostcityofAtlantisbeneaththewaterssurroundingtheislandhowever,Rackhamisinactualityusingthehalf-humanmonsterstoplunderthelostcityofitstreasures. Shakira(BerylCunningham),avoodoopriestessintheemployofRackhamforetellsdeathanddestructiondescendingupontheisland. Thepriestess'prophecyisfulfilledasthefilmendswithClaudeandAmandaattemptinganescapefromagun-wieldingRackham,acrazedShakira,uncontrolledfishmenandtheveryvolcanothatdoomedAtlantiswhichawakensandthreatenstosendwhatunsubmergedlandmassremainstooblivion.…