Sanmu, Japan offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Sanmu is known for Kujukuri Beach, a popular destination for surfing and beach activities. The best time to travel to Sanmu, Japan, is in late spring (May), when the average air temperature is around 20°C (68°F) and the water temperature is approximately 18°C (64°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!