We stayed at La Mer Cave House for one night at the beginning of September. If you’re looking for an authentic cave house experience, I would definitely recommend. The views are stunning and the house is tucked away in the heart of Oía (though in order to see sunrise/sunset you will have to walk 2 minutes up the road). Despite no air con, the place remained relatively cool, increasingly so the further inside we went, and there was a de-humidifier too. We really enjoyed our stay!