Originally released as a motion picture in 2005.

Special features: filmmakers' commentary; writers' commentary; "Into the cave" featurette ; "Designing evolution : tatopoulos studios" featurette.

Director of photography, Ross Emery ; editor, Brian Berdan ; music, Reinhold Heil, Johnny Klimek.

Cole Hauser, Morris Chestnut, Eddie Cibrian, Rick Ravanello, Marcel Iures, Kieran Darcy-Smith, Daniel Dae Kim, Lena Headey, Piper Perabo.

While on a dig in a Romanian forest, a group of scientists make a startling find. Dating back to the 13th century, they find a huge abbey, which was built over the entrance to a massive network of subterranean caves. Eager to learn what lies within the caves, the scientists discover to their peril that a large part of the cave system is under water. The scientists hire a team of American spelunkers who are trained in exploring underwater caves. The team is led by brothers Jack and Tyler. Armed with new high-tech SCUBA gear, Jack, Tyler, and the rest of their crew dive in to investigate the caves. A mishap traps them in a cavern beneath the surface, and they soon discover they are not alone.

MPAA rating: PG-13; for intense creature violence,CHV rating: 14A; frightening scenes, coarse language.

DVD, region 1, 2.40:1 anamorphic widescreen ; Dolby Digital, 5.1 surround, Dolby surround.

In English or French with optional English or French subtitles; closed captioned.