Yalan Dunya Cave lies inland from Gazipasa, a cool limestone break from the coast. It is a local excursion rather than a headline cave, but the stalactites, chambers, and sudden drop in temperature make it a useful half-day option when the beaches are too hot.
Check locally before going, because opening arrangements can be less predictable than at Turkey's major cave sites. If you have a car, combine it with a slow drive through the villages and banana-growing country behind Gazipasa.