Pozo de la luna

The approach is a descent along a steep limestone wall to the cave entrance at 17m. The opening itself is easy to miss without local knowledge — a guide is essential from the start. Inside, the corridor is single-file travel over rounded boulders and large pebbles, the ceiling above throughout. Torches on from the beginning: once past the entrance, ambient light does not reach.

The halocline appears partway through the 50m passage. It announces itself not as turbidity but as a shimmering, refracting boundary — where cooler freshwater from the island's limestone interior floats above the saltwater below. Passing through it produces a brief visual distortion, the underwater equivalent of a heat mirage on tarmac. Maintain orientation, follow the guide, and keep moving.

At the end of the corridor the cave opens into a round chamber. Above is a circular hole in the cave ceiling. Divers ascend through it and surface in the Moon Pool: an air pocket inside the rock, open sky visible above through the circular opening. The moment of removing a regulator to breathe cave air and look up at that ring of light is what names this site.

Haloclines are not common in Mediterranean cave diving. This feature is both consistent and distinctive — a documented freshwater intrusion from Menorca's limestone groundwater system, reliable enough to count on rather than hope for. The Moon Pool arrival moment compounds it: the journey through the halocline corridor resolves into a surfacing experience with no equivalent on the island. Pozo de la Luna is close to the Cap d'en Font cave system and typically dived as part of an SE coast cave day, but it offers a distinct experience that the other chambers in that network do not.

The cave entrance is not visible from the surface — a guide who knows this specific entry point is not optional. Torch discipline matters throughout the corridor. The cave runs cold year-round; 14-15°C inside regardless of the season means the 7mm wetsuit you wore in the bay will serve you, but only with a hood. The halocline visual distortion is normal; expect it, follow your guide, and maintain buoyancy trim through the boundary layer. The site lies outside the Reserva Marina de la Illa de l'Aire — the reserve boundary runs further east — so no reserve permit is required.