I had the opportunity to stay one night at the Cueva de las Estrellas and one night at the Cueva del Mar, they are next to eachother, exactly by the sea.
Both caves where very clean, they where brand new and very well equipped.
Cozy and modern design.
The best thing was the sound of the waves during the night and the experience to open your door in the morning, exactly 3 meters from the sea.