A shallow, northern extension of San Francisco Bay in California.
San Pablo (AVP-30) was laid down on 2 July 1941 302 by the Associated Shipbuilding Co., Seattle, Wash.; launched on 31 March 1942; sponsored by Mrs. W. A. Hall; and commissioned on 15 March 1943, Comdr. R. R. Darron in command.
Following commissioning and outfitting, San Pablo conducted shakedown in the Puget Sound area and then steamed to San Diego for readiness training. On 15 June, the small seaplane tender departed the west coast and headed for the South Pacific. At Espiritu Santo, San Pablo embarked marines and deck cargo; then proceeded to Noumea, New Caledonia. After offloading there, she went to Brisbane, Australia, to pick up the flight crews and aviation supplies, including spare parts and fuel, of patrol squadron VP-101; then returned to Noumea to commence operations as tender and base for "Black-Cat" (night-fighting, air-search, and reconnaissance) PBM's and PBY's.
With VP-101 and assigned crash boats, San Pablo formed Task Group 73.1 and established their seaplane base by charting the bay, setting out mooring and marker bouys, and constructing quarters for squadron personnel at nearby Honey Hollow. They also built an advanced base at Samarai, Papua, New Guinea. For the next several months, the "Black Cats" operated from these bases, preying on enemy shipping along the coasts of New Guinea, New Britain, New Ireland, and in the Bismarck Sea. They inflicted great losses on inter-island barge traffic as well as to heavy shipping; harassed enemy troops with night bombing and strafing missions; conducted photo intelligence operations; provided at-sea search and rescue support for downed Army fliers and sailors of sunken vessels; and carried high ranking officers, friendly coast watchers, and native guerrilla units.
While continuously on the alert for enemy air attack, San Pablo Sailors worked around the clock to fuel, repair, arm, and control the seaplanes; and to feed and care for their crews. On 9 October, she was relieved by Half Moon (AVP-26) and sailed to Brisbane for long needed repair, replenishment, and shore leave. She returned to Noumea on 20 December and resumed operations with VP-52. During January 1944, she gave direct support to the force which occupied Finschhafen, New Guinea, and helped to establish a new advance base at Langemak Bay. At times, she also tended the planes of VP-34, then flying rescue missions for the 5th AAF from Port Moresby. She once temporarily based two OS2U scout planes from Boise (CL-47).
From Langemak Bay, San Pablo's planes helped to prevent the Japanese from supplying garrisons on Rabaul and Kavieng. On 25 February, relieved again by Half Moon, San Pablo returned to Noumea for repairs alongside Dobbin (AD-3). During the work, she assisted in removing a screw from Aaron Ward (DM-34) using her seaplane winch. This speeded repairs to the destroyer-minelayer and allowed her to reach Ulithi in time to prepare for the forthcoming Okinawa campaign.
By 24 March, San Pablo was conducting operations at Seeadler Harbor, Admiralty Islands, with VP-33 and VP-52 planes. They carried out night bombing missions in the Carolines and search flights by day. The pace had so quickened by the end of March that Tangier (AV-8) was brought in to help carry the load. On 13 May, they moved to Hollandia to patrol the approaches to Wakde Island prior to Allied landings there. Relieved by Orca (AVP-49) on 26 May, San Pablo then refueled PT boats at Humboldt Bay and transported personnel and cargo between Manus, Seeadler, Emirau, and Wpendi. On 19 August, she commenced ASW patrols with VP-11 planes at Woendi and, during October and November, conducted ASW operations off Morotai and Hollandia. Later relieved by Saw Carlos (AVP-51), she moved to Anibong on Bay, Leyte, to support planes conducting search missions in the Philippines.
On 8 December, San Pablo received survivors of Mahan (DD-364) who had been picked up by one of her PBM's after that destroyer had suffered three kamikaze hits and sank in Ormoc Bay. She then joined a convoy en route to Mindoro and came under severe attack by suicide planes for ten consecutive days. Most of the kamikazes were beaten off by AA fire from the convoy screen or by CAP planes. However, one hit an ammunition ship which completely disintegrated in a tremendous explosion, and another crashed into a Liberty ship and caused severe damage. On 30 December at Mindoro, a Val barely passed astern of San Pablo and crashed into Orestes (AGP-10), wounding four San Pablo men with shrapnel. On the 31st, a Betty bombed nearby Porcupine (IX-126) and then crashed into Gansevoort (DD-608). Through January and early February 1945, San Pablo made search missions in the South China Sea and along the China coast with VPB-25 and VP-33 squadrons. On 13 February, she was relieved by Tangier and returned to Leyte.
Through April, she escorted LST-777, Chestatee (AOG-49), and various merchant transports between Leyte and Palawan. She then steamed, via Morotai, to Manus. At the end of June, she moved to Samar and the Lingayen Gulf area for air search and rescue operations in the South China Sea-Formosa area. These lasted until 15 August when she received orders to cease offensive operations. On 2 September, the day of Japan's formal surrender ceremony, San Pablo was in Lingayen Gulf providing ASW patrols to cover occupation convoys bound for Japan.
San Pablo returned to Bremerton, Wash., on 17 November to prepare for inactivation. She moved to Alameda, Calif., on 25 March 1946 and remained idle until placed out of commission, in reserve, on 13 January 1947.
Following conversion to a hydrographic-survey vessel, San Pablo was reconunissioned on 17 September 1948 at San Francisco, Comdr. T. E. Chambers in command.- She conducted shakedown training off- San Diego from 29 October to 15 November and was then ordered to report to the Norfolk Naval Shipyard. San Pablo reached Portsmouth, Va., on 14 December and completed outfitting prior to sailing on 3 February 1949, in company with Rehoboth (AVP-50) for oceanographic work in the western approaches to the Mediterrannean. Calling at Ponta Delgada, Azores; Plymouth, England; Gibraltar; and Bermuda; she returned to Philadelphia on 18 April. During the remainder of the year, she conducted two similar cruises to survey and measure ocean currents; and, during the last, made a study of the North Atlantic Drift. She included in her ports of call Scapa Flow; the Orkney Islands; Oslo, Norway; and Copenhagen, Denmark. San Pablo was redesignated AGS-30, effective 25 August 1949.
Beginning 18 January 1950, she conducted a survey of the Gulf Stream; and, from 5 to 26 June, served as Survey Headquarters Ship for a group of American and Canadian vessels engaged in broad coverage behavioral studies of that massive current. After a cruise to Casablanca, French Morocco, in July and August, she returned to the east coast of the United States to conduct survey operations between New London and Key West for the remainder of the year.
During 1951, San Pablo conducted oceanographic studies during various cruises, ranging from Scotland to the Mediterranean and along the coast in the Narragansett Bay operating area. Her tasks included making accurate profile studies of the ocean bottom for the purpose of evaluating new sonar devices. In 1952, she spent the majority of her time in the North Atlantic, and devoted the latter part of the year to training operations out of Norfolk. From 1953 through 1968, San Pablo alternated between the North Atlantic and the Caribbean conducting studies on salinity, sound reflectivity, underwater photography techniques, deep bottom core sampling, bottom profile mapping, subsurface wave phenomena, and other topics still classified. For several months during 1965, she utilized the port and docking facilities at Rosyth, Scotland, as a temporary home port, courtesy of the British Royal Navy. From 1 January to 29 May 1969, she underwent inactivation at Philadelphia.
San Pablo was decommissioned on 29 May 1969 and struck from the Navy list on 1 June. After being used by the Ocean Science Center of the Atlantic Commission, Savannah, Georgia, she was sold on 14 September 1971 to Mrs. Margo Zahardis of Vancouver, Wash.
San Pablo earned four battle stars for World War II service.