Synopsis for
The Abyss (1989) More at IMDbPro »

Virgil 'Bud' Brigman (Ed Harris) and his team are rig workers on an experimental deep water drilling platform. When the US Navy loses submarine to what they think is a "Russian attack sub", Deep core (the drilling rig) is dispatched to save the sailors.

What should have been a routine search and rescue, has a shadow lurking over it. Because of the possibility of a new Russian weapon, the US Military has authorized Lt. Hiram Coffey (Michael Biehn) to take one of the Nuclear weapons from the sub and arm it just in case the Russians attack.

What no one knows is that deeper in the sea, a race of aliens has made home and is quite displeased in seeing us kill one another on the surface. When they begin to make their presence known, Coffey panics and sends the nuke down to them to "destroy the threat".

After defeating Coffey, Bud does a record breaking dive down to the nuke in an attempt to disarm it. He succeeds, but doesn't have enough "air" to make it back to the rig. He is rescued by the aliens who reveal to him what they plan to do to the human race. Mile high tidal waves begin to converge on all the coasts of the world. The world is thrown in panic. Then, at the last possible second, the tidal waves dissipate

The world gets the message that they should stop killing one another. Bud then introduces the aliens to the world.