James Cameron, who proclaimed himself the "king of the world" upon winning three Oscars for his 1997 film Titanic, can now proclaim himself king of the underworld as well. On Monday the moviemaker became the first solo aquanaut to reach the deepest recess of the Mariana Trench, touching down at the Challenger Deep site about 11 kilometers below the surface of the Pacific Ocean.

Cameron, who also directed the first two Terminator movies as well as Avatar, piloted his DEEPSEA CHALLENGER submersible on the seven-hour round trip, spending about three hours at the deepest spot on the planet to collect samples for marine biology, microbiology, astrobiology, marine geology and geophysics research. Based on the success of this expedition, he plans to explore other deep-water habitats, including the New Britain Trench in the Solomon Sea and the Sirena Deep portion of the Mariana Trench.

The DEEPSEA CHALLENGER, 7.3 meters long but only 109 centimeters wide, includes a number of features designed to aid Cameron on his expedition. The sphere-shaped pressurized cockpit features a mechanism that collected moisture from Cameron's breath and sweat in the air into a plastic bag, where it could have been accessed if Cameron was running low on drinking water. The vessel itself descends vertically, with the cockpit oriented at the bottom, below a 2.4-meter-long panel of lights and batteries. About 70 percent of the vessel's volume is taken up by syntactic foam made from millions of hollow glass microspheres suspended in an epoxy resin.

The director is no stranger to the abyss, having made more than 70 deep submersible dives, nearly half to the Titanic, prior to Monday's endeavor. Fifty-one of his dives were in Russian Mir submersibles to depths of less than five kilometers. Cameron has also invested millions to build robotic submersibles that enabled him to capture underwater footage for his IMAX Titanic documentary called Ghosts of the Abyss and for a Discovery Channel film about the Bismarck, a German battleship sunk by Allied forces in the North Atlantic in 1941.

The only other manned mission to the Challenger Deep was completed in January 1960 by then U.S. Navy Lt. Don Walsh and Swiss oceanographer Jacques Piccard aboard the bus-sized bathyscaph Trieste. Walsh and Piccard spent about 20 minutes on the ocean floor before resurfacing. Walsh served as a consultant for Cameron's expedition and was aboard the expedition ship Mermaid Sapphire, from which Cameron launched the DEEPSEA CHALLENGER.

Built in 1953, the Trieste's 15-meter-long floats contained 70 tons of gasoline to help with its descent. As the depth increased, the gasoline compressed, further reducing the vessel's buoyancy. The Trieste featured a two-person cabin that could carry enough oxygen for 48 hours. The blimp-shaped vessel had two small cone-shaped windows that gave its occupants a wide-angle view of the surrounding sea and carried mercury-vapor floodlamps, a camera with an electronic flash, an echo-sounder with a range of about 180 meters and a telephone that received and transmitted directed sound waves through the water. As Scientific American reported in its April 1958 issue, the bathyscaph helped ocean explorers "overcome the bugaboo of the great pressure in the ocean deeps and shown that man can journey there quite safely and comfortably."

Only two other vessels have been to Challenger Deep—Japan's Kaiko robotic sub in March of 1995 and the Nereus, built by Woods Hole Oceanographic Institution engineers, in May 2009. Researchers at the University of Aberdeen Marine Biodiscovery Center (MBC) in Scotland are studying a bacterial species—Dermacoccus abyssi sp. nov.found in mud samples from one of the robotic missions to determine whether marine organisms might be used as a source for new chemical compounds, which could be used to develop novel treatments for cancer, inflammation, infection and parasitic diseases.

Like any good filmmaker, Cameron has even planted the seeds for a sequel (perhaps several). The director-turned-aquanaut's voyage was cut short by a hydraulic leak that prevented the submersible's mechanical arm from working properly, according to OurAmazingPlanet.com. Cameron, who had planned to spend six hours at the bottom, was also unable to launch the DEEPSEA CHALLENGER's unmanned lander containing cameras and baited plastic traps to attract, observe and possibly collect any predators who might be swimming through his landing zone. It's likely the Mariana Trench hasn't seen the last of the Titanic director.

James Cameron photo courtesy of Mark Thiessen/National Geographic