DSV-4 originally had a maximum dive depth of 6,500 feet (2,000 m), as all Alvin-class DSVs did at first. It was redesigned to dive to 20,000 feet (6,100 m) and refitted in 1984. With the refit of DSV-4, the bathyscaphe DSV-1 (formerly known as Trieste II) was retired from service.
In 1985 the Sea Cliff made a record dive for this vessel type by diving 20,000 feet off Guatemala's Pacific Coast. The crew of the dive consisted of pilot Lt. Alan Mason and co-pilot Chief Petty Officer David Atchinson.
DSV-4 has a plug hatch 2 feet (0.61 m) in diameter, held in place mechanically with hatch dogs and, while submerged, by the pressure of the water above it. DSV-4 can dive 5,000 feet (1,524 meters) deeper than the famed Alvin; however, the Super Alvin-class replacement for DSV-2 is designed to dive to 22,000 feet (6,705 meters).