Lords of the Deep

Lords of the Deep is a 1989 science fictionhorror film about an underwater colony being attacked by alien life forms. Starring actors included Bradford Dillman and Priscilla Barnes.

Set on board an undersea laboratory in a near future ocean where the Earths ozone layer has been depleted and new means of habitation and survival are being explored, biologist Claire is working on an unknown specimen when she experiences psychic visions. Meanwhile a routine crew replacement is inbound in a minisubmarine when an undersea quake occurs. Contact is lost with the sub and a search sub is sent out to investigate the silence while one of the labs crew works on exterior repairs in a diving suit. The search sub discovers the relief sub is now derelict and the hatch blown with no sign of the crew and is promptly attacked by large stingraylike creatures. After repelling one creature with an electrical discharge the sub is overpowered by more of the rays and contact is lost.The crewman working outside the lab is then attacked and the crew find him half out of the labs moon pool. When his mask is removed it is revealed he has been totally transformed into a gelatinous mass. Commander Dobler orders the mass quarantined, but Claire and Barbara the medical officer override him and the mass is moved to the lab where it is discovered to be both identical in composition to the substance Claire was studying, and also to be mutating into a mansized stingraylike creature. ........

Source: Wikipedia