After a sinkhole opens in the Antarctic Ocean just off the Ross Ice Shelf a team is sent to investigate and map the uncharted depths. Unfortunately, the adventure is derailed when the team is forced to fend off monstrous sea-life like giant spider crabs, suicidal octopi and a pod of raging-mad killer whales. The coup de grace, though, is the giant eel-like monster that destroys two of the team's exploratory submersibles before trying to take a bite out of the hovering underwater complex itself ... threatening to sink it to the bottom of the 30,000-foot-deep chasm.