Mystery of the Eternal Night (Tayna vechnoy nochi) (DVD)

An underwater explosion at the bottom of the Pacific wreaks havoc with underwater eco-systems. The likely cause appears to be radiation and a new element. Scientists head to the ocean depths to figure out what's going on. They soon discover new species of fish (including giant squids), but most notably a hub of brilliantly-colored, new undersea plants, which appear to be resistant to radiation and, in fact, are irradiated themselves.