1.  What is a trench in the ocean?  2. there have been 22 trenches within the ocean that have been identified.  18 trenches are in the pacific ocean, 3 in the Atlantic and 1 in the Indian ocean.  The Mariana is east of the Mariana islands in the Pacific ocean.

6.  The deepest trench within the Mariana trench system is the Challenger trench which is 36, 201 feet deep.  Mt. Everest is 29, 035 feet high so, we could place this mountain in the trench and still have 7,000 feet left.

8.  This trench is used as a passage for submarines.  The Mariana trench is by far the deepest point in the ocean.  You cannot scuba dive to this location because it is so deep. You would never survive the pressure.

9.  The Challenger Deep is the deepest surveyed point in the oceans, with a depth of approximately 11,000 meters (36,000 feet). It is located at the southern end of the Mariana Trench near the Mariana Islands group. The Challenger Deep is a relatively small slot- shaped depression in the bottom of a considerably larger crescent-shaped trench, which itself is an unusually deep feature in the ocean floor.

10.  The very first expedition to this area was by the HMS Challenger from 1872 to 1876.  HMS Challenger was a steam-assisted Royal Navy Pearl-class corvette launched on 13 February 1858 at the Woolwich Dockyard. She was the flagship of the Australia Station between 1866 and 1870.

12.  She was picked to undertake the first global marine research expedition: the Challenger expedition. To enable her to probe the depths, all but two of the Challenger's guns had been removed and her spars (keeps sails in place) reduced to make more space available. Laboratories, extra cabins and a special dredging platform were installed.

13.  She was loaded with specimen jars, alcohol for preservation of samples, microscopes and chemical apparatus, trawls and dredges, thermometers and water sampling bottles, sounding leads and devices to collect sediment from the sea bed and great lengths of rope with which to suspend the equipment into the ocean depths. In all she was supplied with 181 miles (291km) of Italian hemp for sounding, trawling and dredging.

14.  The Challenger carried a complement of 243 officers, scientists and crew when she embarked on her 68,890 nautical mile (127,670 km) journey. Despite the great success of the Challenger Expedition, the Challenger suffered an ignominious fate. She was commissioned as a Coast Guard and Royal Naval Reserve training ship at Harwich in July 1876.

15.  She was paid off at the Chatham Dockyards in 1878 and remained in reserve until 1883, when she was converted into a receiving hulk in the River Medway, where she stayed until she was sold to J. B. Garnham on 6 January 1921 and broken up for her copper bottom on 1921.[1] Nothing, apart from her figurehead, now remains. This is on display in the foyer of the National Oceanography Centre, Southampton. The United States Space Shuttle Challenger was named after the ship[2]

16.  The Trieste was a Swiss-designed, Italian-built deep-diving research bathyscaphe ("deep boat") with a crew of two, which reached a record maximum depth of about 10,911 meters (35,797 ft), in the deepest known part of the ocean on Earth, the Challenger Deep in the Mariana Trench near Guam, on January 23, 1960.  Fifty years after their historic voyage, the two- man crew remain the only human beings to ever reach the bottom of Challenger Deep. The vessel is currently on display at the U.S. Navy Museum.

19.  Since the Trieste was the first sub to be used to explore the vast depth of the ocean, there were many unusual creatures that were discovered by the men in this sub.