Mangareva, French Polynesia offers 1 beach perfect for sunbathing, surfing, swimming, and more. Mangareva, Tuamotu Gambier Islands, French Polynesia, is known for its stunning lagoon, the historic St. Michael's Cathedral, and the pearl farms. The best time to travel to Mangareva, French Polynesia, is from May to October, with average air temperatures around 77°F (25°C) and water temperatures near 79°F (26°C). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!