Ballıkayalar is Gebze's strongest outdoor reason to detour from the Marmara motorways. The protected limestone valley runs for about 1.5 km, with rock walls, a stream, small waterfalls after wet weather, and picnic spots under the trees.
The park is especially known among climbers; the cliffs are one of the Marmara region's regular sport-climbing areas. Hikers do not need ropes to enjoy it, but wear shoes with grip and expect rougher ground than a city park.