After a sluggish half hour, this well-crafted adventure kicks into high gear and never lets up. A veteran diver (Richard Roxburgh) is hired by a cocky, thrill-seeking financier (Ioan Gruffudd) to map an underground river through a network of spectacular caves and tunnels in Papua, New Guinea. But he hasn’t counted on working with his estranged son (Rhys Wakefield), an expert climber, and tempers flare in the close quarters as a cyclone raging aboveground interrupts communications with the surface crew. James Cameron served as executive producer, and the 3-D process he perfected for Avatar adds depth to the underwater scenes and texture to the subterranean settings (most of which were shot on a soundstage). Roxburgh invests his character with a harsh fatalism that echoes the screenplay’s allusions to ancient Greek myths about Hades, patricide, and hubris. Alister Grierson directed.