Rena's cave house was something out of a dream. Her hospitality was lovely (The house was stocked with a fresh loaf cake as well as some local wines). I would only recommend that you prearrange a meeting point with Rena, so that her porter can escort you to the house itself. The cliffside of Oia is saturated with houses of this type making it difficult to find on your own. I am visiting Rena's again in a few weeks, reinforcing my wonderful experience.