Tanapag, Northern Mariana Islands offers 2 beaches perfect for sunbathing, surfing, swimming, and more. Tanapag, Saipan, Northern Mariana Islands, is known for its proximity to the historic World War II site, the Tanapag Harbor. The best time to travel to Tanapag, Northern Mariana Islands, is from December to June, with average air temperatures around 80°F (27°C) and water temperatures near 82°F (28°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!