Seven Days from Now

AKA Abandon Ship! A luxury cruise liner hits a mine and sinks in the shark infested south Atlantic. Survivors gather around an overcrowded lifeboat. Alec Holmes (Tyrone Power) takes command after the captain's death. With dwindling supplies and rescue unlikely, he faces an impossible choice with greater and greater urgency.

They probably filmed most of this in a giant water tank but it looks like it's the open ocean. The boat always looks dangerously close to sinking and the waters get really rough. This is actually a very harrowing tale. The high stress situation is great for pulling out the characters. There is something basic about their predicament. It is primal. The story is very compelling.