Derwent Valley, Australia offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Derwent Valley, Tasmania, Australia, is known for the historic Willow Court Asylum and the scenic Mount Field National Park. The best time to travel to Derwent Valley, Australia, is during the summer months of December to February, when the average air temperature is around 20-25°C (68-77°F) and water temperature is approximately 16-18°C (61-64°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!