The Abyss (1989)

  I don't think I've ever seen this movie from the beginning.  I always caught it about thirty min to halfway in and watched from there.  I didn't realize how quickly they show you the aliens.

Oh, yeah.  If you haven't seen the movie, **SPOILER** it's about aliens **END SPOILER**.

A US nuclear sub sinks into deep water after seeing something weird on their radar.  A deep-sea mining operation is pulled in to go search the wreck for survivors, since the Navy team would take too long to get there and there's a hurricane on the way.  They send a SEAL team down, led by a man named Coffey (Michael Biehn), to lead the operation.  This does not go over well with Bud (Ed Harris), the civilian leader of the miners, especially since they are also bringing down his estranged wife, Lindsey (Mary Elizabeth Mastrantonio).  A series of disasters occur, with Coffey beginning to succumb to pressure-induced psychosis and confusing aliens with Russian subs.  He removes a warhead from the stricken sub and brings it on board the mining rig.

This won an Oscar in 1990 for Best Visual Effects and most of the smaller ones still stand up.  The really huge set pieces have that seam all the way around, where the computer graphic was added in, but Cameron has always been a front-runner for special effects.

A lot of the suspense in the film comes from all the underwater work.  You can feel the characters' isolation, their panic as things start to go wrong.  When one of the helmets is breached and begins filling with water, I think everyone can imagine that kind of fear.  Space is a slightly different ballgame, since so few people have experienced it, but I think everyone who has ever been in water has had a near-drowning, just enough to make you never want to repeat it, so it's a more accessible fear.  Even though deep-sea vessels and space shuttles are basically the same things:  little safe spaces inside enormous spaces that will kill you if you move from one to the other.