This movie had a crew going underwater for some kind of expedition. There they encounter an aquatic being which takes the form of water. Some time later, there is a scene involving missiles or explosives set at the bottom of the seabed to kill the being. The lead character realizes that the being is not evil, decides to sacrifice himself to stop the explosives. While there, the being takes him back to its ship and creates a breathable environment inside water walls. Also it manages to capture TV channels shown on a suspended water screen. The world or city is about to be destroyed by the being with a huge tidal wave. The hero convinces the being and the tidal wave is withdrawn. The final scene shows a huge ship emerging from the sea.
Which movie is this?