Challenger Expedition, an exploring trip made in 1872–76 to study the ocean bottom and undersea life. The Challenger, a British naval vessel, carried special scientific equipment and a party of leading scientists. The ship sailed around the world, covering 70,000 miles (113,000 km) in three and a half years. The ocean was dredged for ooze, dragged for fish, and sounded for depth. Previously unknown plateaus, currents, submerged volcanoes, depths, and precipices were discovered. Thousands of specimens of plants and animals were brought up and preserved; many of them represented species never before seen by man. Results of the investigation were published in 50 volumes, containing 29,000 pages.