The island of New Guinea in the Pacific Ocean sits on the equator, where immediately next to a richly-colored coral reef, a sharp underwater cliff drops 1,000 meters. A long-awaited exploration into the little-known depths of this tropical sea is finally about to start. NHK has teamed up with eminent marine biologist Mark Erdmann, the man who discovered the coelacanth in Indonesia. A spherical transparent submarine is used as the team encounters true living fossils, one after another. During their last dive, in the darkest depths of caves in the deep-sea cliff, the crew encounters a huge, unknown exotic fish. In a huge submarine canyon in California"s Monterey Bay, there"s an illuminating twilight zone. It"s a world of countless exotic creatures -- including sparkling jellyfish and deep-sea fish that give off flashes. NHK"s crew mounted an ultra-high sensitivity 4K camera specifically developed for deep-sea filming onto the latest submarine and ventured out on a new adventure. Together with experts in the field, they attempted to film bioluminescent creatures in their natural environment fathoms deep in the ocean. Observe the amazing mystery of these enlightening life forms that have survived harsh pitch-black environments.