USS Dolphin

USS Dolphin 555

The Deepest-Diving Submarine Ever.

555 USS Dolphin

The deepest diving submarine in the world, Dolphin is responsible for many “firsts”, but is not primarily associated with any specific historic event or time frame during her nearly forty years of service. Rather, it is her unique, extreme deep-diving capability that sets her apart and has continually placed the vessel at the forefront of undersea naval research during her entire career.

In November 1968, she set a depth record for operating submarines that still stands. In August 1969, she launched a torpedo from the deepest depth that one has ever been fired. Employed by both Navy and civilian researchers, the submarine is equipped with an extensive and impressive instrumentation suite that can support multiple missions. Since the boat’s commissioning in 1968, it has amassed a startling record of scientific and military accomplishments.

The boat was designed to be easily modified both internally and externally to allow the installation of special military and civilian research and test equipment. A recent example of this modification for research and development was Dolphin’s test run of the Navy’s newest sonar system. She is presently configured to conduct extensively deep water acoustic research, oceanic survey work, sensor trials, and engineering evaluations.

Specific stories of her various achievements and contributions include:

  • Development of a Laser Imaging system of photographic clarity
  • Development of an Extreme Low Frequency (ELF) antenna for TRIDENT
  • Evaluation of various non-acoustic ASW techniques
  • Evaluation of various low probability of interception active sonars
  • First submarine launch of a MOSS system
  • First successful submarine test of BQS-15 sonar system
  • Development of highly accurate (10 cm) towed body position monitoring system deepest launching of a torpedo
  • Development of a new Obstacle Avoidance Sonar system
  • Development of a highly accurate target management system
  • Evaluation of a possible “fifth force of nature”
  • First successful submarine-to-aircraft optical communications
  • First successful submarine-to-aircraft two-way laser communication
LOA 151′ 11″
Displacement 875 Tons full load
Diesel Engines 2 X General Motors V71 12-cylinder engines, 425 hp
Electric Motors 2 X main 250 KW generator motors (880 amp ea.) w/ 2 x 126-cell main storage batteries
Cruising Speed Surfaced 3-4 knots (maximum 10 knots)
Cruising Speed Submerged 7.5 knots

Photo credits: The U.S. National Archives,, Alex Saikowski