A very serious fire in the area of her meat preparation room and freezers brought her construction to a stop, but it resumed and she was launched on 29 October 1964.

At 303 feet (92 m) in length, she and her sister Oceanographer — which entered service nine months before Discoverer — were the largest vessels ever constructed for research purposes at the time.

Home-ported in Miami, Florida, Discoverer's first assignment was to represent the U.S. Government at the 1967 International and Universal Exposition, or Expo 67, in Montreal, Quebec, Canada.

In January 1968 she embarked on a three-month expedition of 20,000 nautical miles (37,000 km; 23,000 mi) to gather information from the depths of the South Atlantic Ocean.

She delivered personnel and equipment to the west coast of Africa, then headed back across the Atlantic to Cape Hatteras, North Carolina.

Under the direction of Dr. Robert S. Dietz, she conducted operations in which data was used in the investigation of geological history and theories of continental drift.

The types of studies carried out were varied and included biological, chemical, geological and physical oceanography, meteorological, and seismic research.

[2] On 23 March 1994, Discoverer was in the Pacific Ocean 300 nautical miles (556 km; 345 mi) east of Easter Island allowing several members of her crew to engage in recreational swimming when a shark attacked the swimmers.

After biting Seaman Phil Buffington, inflicting wounds on his legs that would require over 50 stitches to close, the shark attacked Heather Boswell, a 19-year-old student aboard for a six-month stint working in Discoverer's galley.