Nado Nocturno

In September, swimmers plunge into the spring water of Las Estacas just as twilight gives way to darkness. This is the Nado Nocturno, an open water swimming race set in the crystalline natural river of Las Estacas, located in Tlaltizapán in the state of Morelos, Mexico. As night falls, the stillness of the water embraces the field, and participants navigate the channel guided by the glow of the moon overhead.

The nocturnal descent down the Las Estacas spring river

Organized by Las Estacas, the evening event begins right at dusk, sending swimmers into a quiet stream where silver reflections shimmer across the dark surface. Swimmers choose between three distances of 1,000, 2,000, and 4,000 meters. The 1 km course runs entirely with the current, allowing the natural push of the water to carry you along the riverbanks with effortless rhythm. Navigating an outdoor river corridor in full darkness can feel unfamiliar, but the route is thoughtfully managed from bank to bank. Each participant is supplied with chemical glow lights to ensure clear visibility along the course, while wetsuits and fins are permitted as optional gear for those who prefer extra buoyancy or propulsion. Once the swim concludes, the evening wraps up along the riverbank around a communal bonfire, where swimmers gather to swap stories under the open sky.

Water temperature, limestone origin and the stakes of Las Estacas

The park gives the average temperature of the Las Estacas river as 23 °C (73 °F) and stresses that it is a natural river, not a hot spring. The Las Estacas river is fed by rain that falls across the state of Morelos and slowly infiltrates the subsoil through porous limestone. The constant presence of water at Las Estacas creates a microclimate that is cooler and more humid than the farmland around the park. The name Las Estacas, meaning stakes, comes from the residents who dug stakes into the river shore to control the water level and irrigate their fields. The Las Estacas natural reserve has been a protected area for plants and wildlife since 1998 and covers 652.17 hectares. Las Estacas organises night swims a few times a year, on which swimmers can watch the aquatic life of the park at night.

El Borbollón spring and the seven-meter Poza Azul

The river’s remarkable flow originates at El Borbollón, a powerful natural upwelling spring that pumps out 7,000 liters of subterranean water every second. Because the stream is continuously replenished from the deep aquifer, the water stays immaculately clear and renewed from start to finish. In the dark, this transparency produces striking silver highlights whenever moonlight strikes the rippling surface. Further along the watercourse, the channel expands into the Poza Azul, a natural basin that plunges to a depth of seven meters. This deep section serves as a celebrated hub for diving and underwater recreation during the day, revealing the full vertical scale of the spring system.

Riparian wildlife and garden dining at Los Amates

By day, the protected canopy overhead shelters a vibrant community of wildlife, including 132 documented species of birds, eight species of mammals, and ten freshwater fish species that inhabit the riverbed. Swimmers who spend the weekend by the water can unwind at Los Amates, the riverside restaurant that serves à la carte dishes and regional buffets set directly amidst the manicured tropical gardens.