Cova de Portals Vells in Mallorca is a hidden gem with sandy beaches and a fascinating cave to explore. The cave, once a quarry for building the Palma Cathedral, boasts impressive sculptures and a rich history. Visitors can enjoy a short hike to reach the cave entrance and marvel at the giant openings that lead into the depths of the cave. Don't forget to check out the petrified sand dune nearby for a unique natural spectacle.