Gumusyaka Merkez, Turkey offers 5 beaches perfect for sunbathing, surfing, swimming, and more. Gumusyaka Merkez, Istanbul, Turkey, is known for its proximity to the Marmara Sea and its tranquil beaches. The best time to travel to Gumusyaka Merkez, Turkey, is from June to September, when the average air temperature is around 25-30°C (77-86°F) and the water temperature is approximately 22-25°C (72-77°F). Sandee provides detailed maps, photos, and reviews from fellow beachgoers to help you Choose Your Beach™ and plan your perfect beach vacation!