Tsukumi, Japan offers 3 beaches perfect for sunbathing, surfing, swimming, and more. Tsukumi is known for its limestone caves and the Tsukumi Dolphin Island. The best time to travel to Tsukumi, Japan, is in April when the average air temperature is around 17°C (63°F) and the average water temperature is approximately 16°C (61°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!