Lake Gölcük - The nature is very nice around this small lake. The lake gives super sight all seasons. Around the lake there's very nice paths for jogging or just walking.There's a restaurent or you can lend "mangals" (braziers) there to cook your own meat (you have to bring your meat) and eat it on the tables near the lake. The weekends it's more crowded. You can get there in 2,5 hours from Istanbul by car.