The "Five Deeps" Expedition and the Challenger Deep

In her more than three years at sea, and over her 68,890-nautical-mile (79,280 mile/127,580 km) journey, the

Challenger circumnavigated the globe, took deep sea soundings, dredged the bottom, and discovered 4,700 new species of marine life.

To measure sea depth, the crew lowered ropes with a weight attached. Then, on March 23, 1875, a sounding taken at a location in the southwest Pacific Ocean between Guam and Palau, revealed the astounding depth of 26,850 feet (8,184 meters).

Challenger was at the southern end of the Mariana Trench, the deepest place on earth, and the location henceforth became known as the "Challenger Deep". Modern soundings at that location have put its depth at 36,070 feet (10,994 meters).

Upon her return, the "Report Of The Scientific Results of the Exploring Voyage of H.M.S. Challenger during the years 1873–76" ran to 50 volumes and was almost 30,000 pages long. Marine specimens that were brought back are still being examined today. To honor Challenger, the marine geological survey ship Glomar Challenger and the Space Shuttle Challenger were named after her.

Three Explorers Challenge the Challenger Deep

On January 23, 1960, Swiss oceanographer Jacques Piccard and U.S. Navy member Don Walsh descended to the floor of the Mariana Trench on board the bathyscaphe Trieste. They reached a depth of 35,813 feet/10,916 meters, but spent only 20 minutes on the bottom after the cold temperatures at that depth caused a crack in one of the outer window panes.

On March 25, 2012, filmmaker James Cameron (Avatar, Titanic, The Abyss) rode a 2.5-story-tall submersible down 6.8 miles/11 kilometers to the bottom of the Challenger Deep. Cameron spent several hours on the sea floor, collecting samples and recording video.

The "Five Deeps"

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Now, almost 150 years after the Challenger Expedition, another expedition called the "Five Deeps", has set out to visit the deepest point in each of the Earth’s five oceans: 1. The Puerto Rico Trench in the Atlantic Ocean (27,480 feet/8,376 meters) 2. The South Sandwich Trench in the Southern Ocean (24,390 feet/7,434 meters) 3. The Java Trench in the Indian Ocean (23,917 feet/7,290 meters) 4. The Challenger Deep in the Pacific Ocean (35,843 feet/10,925 meters) 5. The Molloy Deep in the Arctic Ocean (18,284 feet/5,573 meters).

The expedition is being bankrolled by Victor Vescovo, who has climbed the "Seven Summits" - the highest mountain on each of the earth's seven continents. Piloting a titanium-alloy, 12.5-ton submersible, Vescovo reached the bottom of the Puerto Rico Trench in December 2018. In February, 2019, he reached the bottom of the South Sandwich Trench.

In April 2019, Vescovo is set to dive the Java Trench, and two remaining dives have yet to be scheduled. Along the way, the expedition says they will survey and dive on sites having historical importance or scientific significance.