Zirahuen Open Water

The Zirahuen Open Water is an open water swimming race held in Lake Zirahuén, in the Mexican state of Michoacán. ISHU Sport Experiences organizes the competition, offering five separate distances that range from 500-meter and 1,000-meter sprints to 3,000, 5,000, and 10,000-meter marathon challenges. For the organized race, a monitored perimeter and safety coverage make it possible to swim safely across this wild mountain expanse. Diving in, you feel the brisk mountain cold right away, settling into your rhythm as the wake of the pack stretches across the calm water.

Lake Zirahuén: size, clarity and water temperature

Lake Zirahuén covers 970 hectares and has a volume of 0.216 cubic kilometres. In Lake Zirahuén the surface layer of the water varies between 18.5 °C (65 °F) and 22.5 °C (73 °F), while the deepest layer varies between 16.5 °C (62 °F) and 19 °C (66 °F). The water of Lake Zirahuén is clear enough for the sky and the tall pines around the lake to be reflected on its surface. Lake Zirahuén is also known as Agua Verde. Swimming and kayaking are among the ecotourism activities on Lake Zirahuén, alongside hiking and cycling in the surrounding mountains. Lake Zirahuén takes its name from the village of Zirahuén, which lies on the lake's northern shore.

La Magueyera volcano and the hydrology of Lake Zirahuén

Lava flows from the La Magueyera volcano created the lake long ago by blocking the La Palma river. That volcanic barrier sealed the water into an enclosed endorheic basin within the state of Michoacán. Today, the catchment area covers roughly 270 square kilometers, capturing an annual average runoff of 56 million cubic meters fed by the incoming Manzanillo and Zinamba streams. Lake Zirahuén is monomictic, meaning its water column thermally stratifies between April and October. While hydrological measurements show that the surface level has receded gradually since the 1940s, the lake remains an imposing, deep mountain reservoir.

The mirror of the gods and the mermaid of Lake Zirahuén

Local residents refer to the lake as the mirror of the gods due to its beauty. Local lore traces the origins of the lake to the tears of the Purépecha princess Eréndira. Kidnapped by a Spanish conqueror, she wept with such inconsolable grief that her tears filled the basin, transforming her into a mermaid who still watches over the deep water beneath you.

The endemic tiro and littoral reeds of Lake Zirahuén

Below the swimmers, the lake bed consists of a sandy bottom partially covered in soft mud. These sheltered waters are the exclusive habitat of the Zirahuén allotoca, or Allotoca meeki, an endemic Goodeid fish known locally as the Zirahuén tiro that exists nowhere else on Earth. Around the edge of the course, 93 plant species colonize the coastline. Tall stands of American bulrush, broadleaf cattails, and black flatsedge fringe the shore, walling off the water from the surrounding mountain hillsides.

The piers and stilt restaurants of Zirahuén village

Back on shore, the village of Zirahuén provides water access through two main piers. The entrance to the waterfront is lined with rustic food stalls and local craft vendors selling handmade goods. Along the water's edge, local fishing families run traditional rustic restaurants. These stilt terraces make the perfect spot to sit after the race, warm up with a hot meal, and watch the evening light settle across the mirror of the gods.