Naval Base Saipan or Naval Advance Base Saipan or Naval Air Base Saipan was a United States Navy Naval base built during World War II to support Pacific Ocean theater of war and the many warships and troops fighting the war. The base was on the island of Saipan in the Northern Mariana Islands. The base was part of the Pacific island hopping campaign. The base construction started after the Battle of Saipan ended on July 9, 1944. US Naval Advance Base Saipan was constructed by the Seabees Naval Mobile Construction Battalions. The base was under the Commander Naval Forces Marianas. Saipan is 12 miles (19 km) long and 5 miles (8.0 km) wide. About 70% of the island was sugarcane cultivation at the start of the base construction. At the start of the Battle of Saipan, the island's population had about 30,000 Japanese troops and about 20,000 Japanese civilians. The city of Garapan was the administrative center for the Saipan governmental district.

Saipan is the largest island and capital of the Northern Mariana Islands, a commonwealth of the United States in the western Pacific Ocean. According to 2020 estimates by the United States Census Bureau, the population of Saipan was 43,385, a decline of 10% from its 2010 count of 48,220.