On a beautiful sunny day off the coast of Costa Rica, a catamaran with 109 people on board suddenly capsized and sank to the bottom of the sea. Floating out in turbulent open water, the survivors have no choice but to wait and hope for rescue. | National Geographic TV

Sea Monsters: A Complete Guide to 19 Mythical Creatures from A-Z

China has marked a leap in deep-sea exploration capabilities with the successful completion of its first manned dive under Arctic ice. Chinese scientists concluded the country's 15th Arctic scientific expedition with the return of the Chinese research icebreaker Xuelong 2 to Shanghai on September 26. With the support of Xuelong 2, mothership Shenhai 1 successfully carried the Jiaolong submersible for its first manned deep dive in the Arctic ice zone. | CGTN