Deep-sea drilling rigs may extract material from more than 1500 m (4900 ft) below the ocean floor. Acoustic positioning beacons are used to keep the rig in place while the drill pipe passes first through the water then into the seabed. The beacons send sonar waves to the surface where hydrophones on the bottom of the ship receive them. A computer-pilot processes this information and uses the tunnel thrusters to compensate for drift and wind.
Scientific research ships date from the 1870s, when the United States, Britain, and Germany launched expeditions to conduct oceanic research. The most significant of these was the HMS Challenger expedition led by Sir Charles W. Thomson from 1872 to 1876.
Scientists aboard the 60-m (200-ft) sailing vessel spent four years studying the ocean terrain and collecting information on thousands of marine species. The Challenger expedition marked the beginning of the fields of oceanography and deep-sea exploration.
A host of vessels have engaged in scientific research since the Challenger's day. These vessels conduct research related to oceanography, geology, meteorology, and marine geography. Some scientific research vessels were specially designed and constructed for that purpose, while others have been converted to research vessels after another career. These floating laboratories feature high-tech computers, sonar, and sampling equipment used to study the ocean and its inhabitants. They are usually manned by a professional crew and a separate cadre of scientists. They range in size from relatively small sailing vessels in the tradition of the Challenger to modern craft as large as 90 m (300 ft) in length.
Research vessels are financed and operated by national governments, educational institutions, private research organizations, or partnerships between these organizations. In the 1960s Global Marine Development, a privately owned company, financed the construction and operation of the 120-m (400-ft) Glomar Challenger, named for the famous 19th century British ocean research vessel. Glomar Challenger was the first research vessel built to drill core samples from the deep ocean seabed. Research scientists aboard the ship found evidence that strongly supports the theory of plate tectonics, which holds that Earth's continents were once joined together and have gradually separated.
The equally well-known research vessel Glomar Explorer was built in 1973, ostensibly to explore the possibility of deep-sea mining for Global Marine Development. Years later, the Central Intelligence Agency revealed that they used the Glomar Explorer to explore and raise a Soviet ballistic submarine that sank in 4,000 m (13,100 ft) of water in the Pacific Ocean. They also revealed that Global Marine's involvement was meant only to serve as a cover for the top-secret operation. Once the covert operation had been completed, the Glomar Explorer spent two years exploring the feasibility of mining manganese from the ocean bottom.