FAS | Military | DOD 101 | Systems | Ships ||||
Index | Search | Join FAS

USS Dolphin (AGSS 555)

USS Dolphin (AGSS 555), homeported at the Naval Research and Development (NRaD) facility in San Diego, is the Navy's only operational, diesel-electric, deep-diving, research and development submarine. It can carry scientific payloads of over 12 tons, a considerably greater capacity than any other deep diving research vessel operating today. Dolphin can also maintain more extensive onboard laboratory facilities than her deep submersible counterparts. USS Dolphin is the Navy's deep diving submarine designed to test advanced submarine structures, sensors, weapons, communications, and machinery systems. USS DOLPHIN serves as a scientific platform capable of operations at unprecedented depths greatly exceeding that of any known operational submarine. 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. Shortly after commissioning, Dolphin established an unmatched world depth record for operating submarines, with a recorded test depth in excess of 3,000 feet.

Because Dolphin was designed as a test platform, it can be adapted to accept projects more easily than most operational submarines. A recent example of this modification for research and development was Dolphin's test run of the Navy's newest sonar system. AS a result of Dolphin's efforts, this new system will now be retrofitted into the fleet. The boat can be modified both internally and externally to allow the installation of special military and civilian research and test equipment. Normally the project's sponsor must fund these modifications, but the boat allows a variety of researchers to attain unprecedented flexibility in deep-ocean missions.

Utilizing a large payload (over 12 metric tons) and a highly versatile instrumentation suite, civilian and Naval activities employ USS DOLPHIN for testing a multitude of technologically advanced and complex equipment. Presently configured to conduct extensively deep water acoustic research, oceanic survey work, sensor trials, and engineering evaluations, USS DOLPHIN operates as a Unit of the U.S. Naval Submarine Force, U.S. Pacific Fleet, under Commander, Submarine Development Group One.

In over twenty years of operations, USS DOLPHIN has proven most successful in assessing "the overall Anti-Submarine Warfare (ASW) significance of deep diving submarines" and exploiting "the limits of present technology in designing for deep depths." Her operations have been broad based and far reaching, and they include development of operational concepts and testing of advanced engineering design features, weapons, launcher and fire control systems, and deep ocean acoustics. Much of this work is necessarily classified, but examples of USS DOLPHIN's specific achievements are listed in the following list.

The Dolphin's Crest

The USS DOLPHIN has achieved a great deal of success in each of her endeavors and has many firsts added to her record. She has indeed proved the feasibility of operating deep in the ocean.

The single most significant technical achievement in the development of the USS DOLPHIN is the pressure hull itself. It is a constant diameter cylinder, closed at its ends with hemispherical heads, and utilizes deep frames instead of bulkheads. The entire design of the pressure hull has been kept as simple as possible to facilitate its use in structural experiments and trails. Hull openings have been minimized for structural strength and minimum hull weight, in addition to eliminating possible sources for flooding casualties.

The USS DOLPHIN 's unique capabilities allow her to conduct independent deep ocean research missions. She is a unique blend of the lessons learned of the past and the most advanced technology of the present. The USS DOLPHIN's continuing contributions to research and development will significantly influence the design of 21st century submarine sonar, weapon, communications, and engineering systems.



165 feet


18 feet

Submerged Displacement

950 tons


Diesel-electric - Two GM 12-cylinder, 425 HP engines



Operating Depth

Greater than 3,000 feet

Submerged Speed

10 knots (short duration), 3-4 knots (sustained)

Scientific Payload

12 tons +

External Mounting Pads

6 port, 6 starboard, forward and aft of sail

Crew Compliment

5 Officers, 46 Enlisted

Operational Endurance

Over 15 days (for long deployments, Dolphin can be towed at 9-10 knots.)


Name Number Builder Homeport Ordered Commissioned Decommissioned
USS Dophin AGSS 555 Portsmouth NSYSan Diego10 Aug 196017 Aug 1968

Sources and Resources

FAS | Military | DOD 101 | Systems | Ships ||||
Index | Search | Join FAS

Maintained by Robert Sherman
Originally created by John Pike
Updated Wednesday, February 24, 1999 6:53:55 AM