Beijing – China livestreamed footage of its new manned submersible parked at the bottom of the Mariana Trench on Friday, part of a historic mission into the deepest underwater valley on the planet. The "Fendouzhe," or "Striver," descended more than 10,000 meters (about 33,000 feet) into the submarine trench in the western Pacific Ocean with three researchers on board, state broadcaster CCTV said. Only a handful of people have ever visited the bottom of the Mariana Trench, a crescent-shaped depression in the Earth's crust that is deeper than Mount Everest is high and more than 2,550 km (1,600 miles) long. The first explorers visited the trench in 1960 on a brief expedition, after which there had been no missions until Hollywood director James Cameron made the first solo trip to the bottom in 2012. Cameron described a "desolate" and "alien" environment.

The expedition has only just begun and already it is producing some stunning footage of the denizens of Earth's deepest abyss. NOAA's Okeanos research ship will spend the next two months cruising the seas above the Mariana trench, using sonar systems and a remotely operated vehicle (ROV) to explore the little known parts of the trench and its surroundings. Footage from the daily dives is being live-streamed, with highlights posted on the expedition site. On 24 April the ROV captured this footage of a beautiful jellyfish (see video above), belonging to the Crossota genus, at a depth of nearly 4 kilometres. On 25 April it filmed a striking, violet sea cucumber swimming above the sea floor (see video below).