Las Conchas

Las Conchas is a gated residential development on the shore about 3 km east of the city of Puerto Peñasco. Most of its houses belong to Americans who take advantage of the short drive from the Arizona border, and they sit in a row facing a long beach of fine sand. The 2010 census counted only 111 permanent residents; in holiday periods the population tops 3,000.

What sets this beach apart from the ones in town is the low tide. The northern Gulf of California has extreme tides, and when the water drops it uncovers wide rocky reefs full of pools where starfish, shrimp and anemones live. Timing is everything: CEDO prints a tide calendar every year.

The Morúa estuary lies directly north of the development, one of several hypersaline estuaries around Puerto Peñasco, with shorebirds, crabs, octopus and snails. A women's cooperative has farmed Pacific oysters there since the early 1980s, and on the estuary's north shore it runs El Barco, a plain oyster bar named after a boat that washed up there, serving raw and steamed oysters, fish tacos and ceviche.

Las Conchas is also home to the field station of CEDO, the Intercultural Center for the Study of Deserts and Oceans. It grew out of a foundation set up in 1977 by Carl Hodges of the University of Arizona, took its present name in 1980, and moved into an unfinished recreation centre in the development that was turned into a biological station. Its Earthship-style visitor centre shows fossils and marine skeletons and has a bookshop. CEDO runs natural history talks and guided outings: estuary walks, kayaking in the estuary channels, tide-pool walks at low tide, days at the Punta Roja cooperative's oyster farm, and trips to Isla San Jorge, the Gran Desierto de Altar dunes and El Pinacate.