The Abyss / Бездна (1989)

At great depth in the Cayman trench wrecked American submarine Montana, containing on Board a ballistic missile. The government sends rescue team of Navy seals are on an underwater experimental station, located not far from the crash site. Together with the team there goes Lindsey Brigman, the designer of the submarine platform, and her husband Virgil. Examining the crash site of the submarine, the rescue team discovers the depths of something unknown. Taking an unidentified object over an enemy submarine, the commander of the Navy decides to destroy it. However, after some time, the team realizes that the depth of the ocean stores not enemy ships, but something more dangerous...