Challenger Deep, the deepest place on earth, lies at the southern end of the Marianas ocean trench in the West Pacific. Ocean trenches, such as the Marianas Trench, mark the subduction zones where an oceanic tectonic plate dives under another plate. The Marianas Trench marks the junction of the Pacific plate and the Philippines plate. The name Challenger comes from the British Royal Navy Survey ship HMS Challenger used on an oceanic survey from 1872 to 1876 and a second vessel Challenger II, which surveyed the area in 1951.
The deep’s closest islands are Fais (one of the Yapp islands) situated 289 km to the southwest and Guam situated 306 km to the northeast. On a chart of the area, Challenger Deep is found at 11 degrees 22 minutes North 142 degrees 36 minutes East.
On January 23 1960, a world record dive in a US Navy submersible took place. Two men in the bathyscaphe Trieste, launched from The USS Lewis, descended in a dive into the Challenger Deep to an estimated depth of 37,800 feet (according to the press release from the US Navy February 1 1960). Other records of the dive revised this depth to 31,815 feet (10,916 meters). The Trieste took 4 hours 48 minutes to descend into the deep. After 20 minutes observing the area with powerful on board lights, it took 3 hours 17 minutes to make the return journey. A bathyscaphe requires incredible strength to survive the pressure at such depth. The Navy press release puts this pressure at 16,833 pounds per square inch. No other manned vessel has made such a descent.
Since 1960, two other measurements of the depth of the Challenger Deep have been made. In 1984, using a narrow multi-beam echo sounder a Japanese survey vessel recorded a depth of 35,838 feet (10,923 meters). The most accurate depth measurement to date is that made by the Kaiko in 1995. The Kaiko, a robotic deep-sea probe, descended into the deep on 24 March 1995. This highly sophisticated probe made by the Japan Marine Science and Technology Center recorded a depth of 35,797 feet (10,911 meters). To put these measurements in context Challenger Deep is over 7 miles deep while Everest our highest mountain is only about 6 miles high.
The Kaiko is unable to repeat this dive, as she was lost in a typhoon in 2003. Currently there are very few unmanned probes available capable of reaching the bottom of Challenger Deep as most are restricted to depths of less than 19,680 feet (6,000 meters) The Nereus probe belonging to the Woods Oceanographic Institution is scheduled for a descent into Challenger Deep in the future.
With so few descents into the depths of Challenger Deep very little is known of its ecosystem. A sample of ooze collected by Kaiko contained come soft-shelled foraminifera. Kaiko’s video camera recorded the presence of a sea cucumber, a shrimp and a scale worm. The reported sighting of a fish similar to a sole by the crew of the Trieste may have been a sea cucumber instead.
Reference Sources:
Absolute Astronomy
Office of Naval Research
BBC News
Economic Expert.com
