Tinian Naval Advanced Base was a major United States Navy sea and air base on Tinian Island, part of the Northern Mariana Islands on the east side of the Philippine Sea in the Pacific Ocean. The base was built during World War II to support bombers and patrol aircraft in the Pacific War. The main port was built at the city and port of San Jose, also called Tinian Harbor. All construction was carried out by the Navy's Seabees 6th Naval Construction Brigade, including the main two airfields: West Field and North Field, serving the United States Army Air Forces's long-range Boeing B-29 Superfortress bombers. The Navy disestablished the Tinian Naval Advanced Base on 1 December 1946.

Tinian, the third of the three largest islands of the Mariana Islands, is located south of Saipan across the 3-mile-wide Saipan Channel. Tinian, north to south, is 12 miles long and east to west 6 miles wide. It has mostly flat terrain, perfect for runways. Along with the other Mariana Islands, Tinian was claimed for Spain by Ferdinand Magellan in 1521. Guam was seized by the United States in the Spanish-American War, and Spain sold the remaining islands to Germany. They were occupied by Japan during World War I and became part of Japan's South Seas Mandate. Japan developed Tinian into a large sugar plantation with a sugar refining plant, and built three small runways on the island. The civilian population was about 18,000 in 1941.

Operation Forager involved the conquest of the Mariana Islands. It was intended that they would be developed into a major naval base for the surface ships and submarines of the Pacific Fleet, as a staging and training area for ground troops, and as a base from which long-range Boeing B-29 Superfortress bombers could attack Japan. American forces landed on Tinian on 24 July 1944, and the island was declared secured on 1 August, although there were still many Japanese soldiers holding out in the caves on the southern end of the island. At the time of the landing, there were three Japanese airfields on the island: two in the north, one with a runway 4,700 feet (1,400 m) long and the other 3,900 feet (1,200 m) long, and one in the west with a 4,000-foot (1,200 m) runway. There was also a small, incomplete airstrip in the center of the island.

Responsibility for construction on Tinian was assigned to the 6th Naval Construction Brigade, under the command of Captain Paul J. Halloran. His staff, along with that of the US Army's 64th Engineer Topographic Battalion, drew up plans for the development of Tinian at Pearl Harbor in the months leading up to Operation Forager. These called first for the rehabilitation of the Japanese airstrips in the north and west, then for them to be lengthened to 6,000 feet (1,800 m) in length so bombers could operate from them, and ultimately for their extension to 8,500 feet (2,600 m) for the B-29s.

For this work, Halloran had the 29th and 30th Naval Construction Regiments. The former, under Commander Marvin Y. Neely, initially consisted of the 18th, 92nd and 107th Naval Construction Battalions, and the 1036th Naval Construction battalion Detachment; the latter, under Commander Jonathan P. Falconer, the 67th, 110th and 121st Naval Construction Battalions. A third regiment, the 49th Naval Construction Regiment, was formed on 2 March 1945 from the 9th, 38th, 110th and 112th Naval Construction Battalions, under Commander Thomas H. Jones.

Elements of the 18th and 121st Naval Construction Battalions landed on Tinian with the assault troops on 24 July, with the remainder arriving on 27 July. That day, the 121st commenced the rehabilitation of the 4,700-foot (1,400 m) airstrip in the north, filling in the bomb and shell craters. By that evening, an airstrip 2,500 feet (760 m) long and 150 feet (46 m) wide was ready for use, and it was fully restored to its full length the next day. On 29 July, a P-47 landed and took off again. The 9th Troop Carrier Squadron was brought forward from Eniwetok, and its Douglas C-47 Skytrains, together with the Curtiss C-46 Commandos of VMR-252, delivered 33,000 rations from Saipan on 31 July. On the return trip they carried wounded to hospitals on Saipan.

A third battalion, the 67th Naval Construction Battalion, arrived on 2 August. With the island declared secure, the seabees were released from the control of the V Amphibious Corps to the 6th Naval Construction Brigade, which became operational on 3 August. Additional naval construction battalions arrived over the following weeks and months: the 92nd from Saipan in August and September; the 107th from Kwajalein on 12 September; the 110th from Eniwetok in September and October; the 13th and 135th on 24 October; the 50th on 19 November, the 9th on 1 December, and the 38th and 112th on 28 December.

The Seabees completed and extended the second Japanese airstrip in the north, which became North Field Strip No. 3 in September. They then rehabilitated the severely damaged airstrip in the west as a 4,000-foot (1,200 m) airstrip for fighter planes. Navy patrol planes commenced operations from the two North Field airstrips, but work to upgrade them to handle the B-29s could not be carried out while they were in use. A new 6,000-foot (1,800 m) runway was built in the west, which became known as West Field Strip No. 3. The airstrip was completed on 15 November. In addition to the runway, there were 16,000 feet (4,900 m) of taxiways, 70 hardstands, 345 Quonset huts, 33 repair and maintenance buildings, 7 magazines and a 75-foot (23 m) tall control tower.