USCGC Triton ( WPC - 116 ) USCGC " Triton " ( WPC - 116 ) , a steel - hulled , diesel - powered " Thetis " - class patrol boat of the United States Coast Guard , was the fourth commissioned ship of the United States to be named for Triton , a Greek demigod of the sea who was the son of Poseidon and Amphitrite . She served almost simultaneously with the submarine of the same name . The contract for her construction was let on 17 November 1933 to the Marietta Manufacturing Company , Point Pleasant , West Virginia . She was commissioned as " Coast Guard Patrol Boat No . 16 " on 20 November 1934 with Lieutenant Commander George C . Carlstedt , USCG , in command . Assigned to the homeport of Gulfport , Mississippi , " Triton " operated in the Gulf of Mexico from at least 1 January 1935 . On 1 July 1941 , four months in advance of the directive whereby the United States Coast Guard was transferred from the United States Department of the Treasury to the United States Navy , " Triton " and five of her sister ships were turned over to the Navy . This action occurred simultaneously with the establishment of the four Sea Frontiers . Four " Thetis " - class patrol boats , including " Triton " , were assigned to the East Coast Sound School , Key West , Florida , for duty as patrol and training vessels . Their collateral duties included operating under the aegis of Commander , Task Force 6 , on Gulf patrol duties . At the time of the Japanese attack on Pearl Harbor , 7 December 1941 , " Triton " was operating out of Key West . In or around February 1942 , " Triton " was classified as a patrol craft and given the hull classification symbol WPC - 116 . Although American warships had been actively engaged in patrol and escort missions in the Battle of the Atlantic even before Pearl Harbor , their techniques for combating the dangerous German U - boat s were , in January and February 1942 , still far from adequate . U - boats operating off the eastern seaboard experienced what they called " the happy time , " before American convoys could be organized . In some cases , Allied ships would be sunk because they were silhouetted by lights in non - blacked out cities along the shoreline . " Triton " s antisubmarine warfare ( ASW ) training missions were conducted along with local patrol and escort duties out of Key West from 1941 into 1945 . She had her first brush with what she presumed to be an enemy submarine on 21 February 1942 . On that day , she made one attack but without success . Over the next few days , upon occasion joined by and , " Triton " conducted more attacks but did not make any strikes . On 9 June 1942 , when reported an enemy submarine on the surface in her vicinity , " Triton " directed " Thetis " to make the search . " Triton " , meanwhile , contacted the submarine " R - 10 " which had been conducting exercises with the patrol vessels in that same area . When took over the job of escorting " R - 10 " back to Key West , Florida , " Triton " joined " Thetis " in search of the submarine . Eventually , " PC - 518 " and " Noa " joined the hunt . " Triton " attacked with depth charge s but , after a further search , concluded that the target was probably a tidal rip in the Gulf Stream , not a submarine . " Triton " s next recorded ASW operation came soon thereafter , during the concentrated search and destroy mission mounted to find the U - boat which torpedoed the American steamer on the night of 10 June . The hunt , which involved radar - equipped United States Army Air Forces B - 18 Bolo bombers , three destroyer s , several PCs , and " Triton " and " Thetis " , took three days . On 12 June , in an area well known for false contacts , " Triton " attacked what she thought to be a submarine but later evaluated to be otherwise . Later that day , although not picking up propeller noises , the contact seemed strong to " Triton " s sonar operator , and the ship attacked . Again , the result was the same — negative . The next day , however , was different . " Thetis " picked up " U - 157 " trying to escape the " dragnet " and destroyed her in a single depth charge attack . That patrol craft recovered two pairs of leather submariner ' s pants and a tube of lubricant marked " made in Düsseldorf . " There were no survivors . " Triton " took part in further attacks , along with the other ships of the hunter - killer group based on Key West ; but , by that point , the enemy submersible had already been killed . " Triton " remained with the Sound School , apparently , into 1945 . On 10 February , while was engaged in " Robot Bomb Patrol , " she picked up what she evaluated as a submarine contact . She and " Triton " , also in the vicinity , then conducted attacks but found no evidence that a kill had been made . " Triton " apparently remained in the Gulf of Mexico region for the remainder of her active service in the Coast Guard . Reverting to Treasury Department control after the end of World War II , " Triton " was reclassified from WPC - 116 to WMEC - 116 ( Medium Endurance Cutter ) sometime in 1966 . Her post - war duty station was at Corpus Christi , Texas , until 1967 . She was sold as government surplus and converted into a twin - deck passenger excursion vessel for Circle Line Sightseeing in New York City . Her two Winton 158 - 6 direct - drive diesels were replaced with two quad sets of four GM 6 - 71 diesels per shaft . Her electrical system was converted to AC with two 60 kW generators each powered by a GM 6 - 71 . She has been a passenger excursion vessel named " Circle Line XVII " since 1973 and is still running as of Fall , 2007 .