These mooring buoys are found opposite Es Geperut, one of the largest beaches in Sant Elm which is partially sheltered by Pantaleu islet. The waters here are reasonably deep which allows bigger yachts to moor here too.

http://www.portbooker.com/es/amarres/espana/mallorca/sant-elm/boyas-de-sant-elm

Playa Sant Elm (Es Geperut) en Andratx

Playa de Es Geperut