Mar Menor: the lagoon of calm, warm… and fragile waters
The Costa Cálida's great saltwater lagoon: shallow water ideal with children, lakeside villages, the Lo Pagán mud baths, and what you need to know about its fragile ecological balance.
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From the air, the Mar Menor looks like a miniature sea sitting next to the big one: a 135 km² lagoon, 21 kilometres long, separated from the Mediterranean by the thin sandbar of La Manga. Its average depth is no more than 4 metres, and that is its charm: calm water, no waves, and quick to warm up. For families with young children, it is often a little paradise.
A ‘minor’ sea with plenty of character
The lagoon is permanently connected to the Mediterranean by natural channels, but its water is saltier and warmer. It has five islands of volcanic origin, including Isla Mayor (or del Barón) and Isla Perdiguera, which dot the horizon.
All around, villages and resorts follow one another: San Pedro del Pinatar, Santiago de la Ribera, Los Alcázares, Mar de Cristal… each with its promenade, jetties and little beaches.
The Lo Pagán mud baths
A local tradition since the early 20th century, the Lo Pagán muds in San Pedro del Pinatar draw fans of natural treatments: you smear yourself in black mud, let it dry in the sun and rinse off in the lagoon. Regulars talk of ‘novenarios’ — nine baths in a row. Children mostly just find it hilarious.
An ecosystem to protect
It must be said honestly: the Mar Menor has been through serious ecological crises. In 2016, an algal bloom (the ‘green soup’) destroyed most of its seagrass meadows; in 2019 and 2021, oxygen depletion caused mass fish deaths. In response, Spain granted it legal personhood in 2022 (Law 19/2022), a first for an ecosystem in Europe.
In practical terms, for your holiday:
- check bathing water quality before swimming, especially in late summer;
- respect protected areas and seagrass meadows;
- choose lifeguarded beaches with children.
Our tips
Water shoes: some lagoon beds are muddy or rocky.
Alternate lagoon and Mediterranean: at La Manga, the two seas are just steps apart — handy if the wind picks up on one side.
Enjoy the evenings: the lakeside promenades come alive at sunset, when the heat eases.
Explore more
Right next door, La Manga and its two seas; further north, the dunes of Guardamar. And to plan your days with the kids, our guide to family days out.
