More than 1,100 athletes from Mexico and at least ten other countries will converge on the Baja California Sur peninsula for the 2025 edition of the “Sea to Sea” Ultramarathon, a three-day endurance race spanning 105 kilometers from coast to coast. The event runs from December 4 to 7, beginning in Los Barriles on the Sea of Cortez and finishing on the Pacific shores of TodosSantos.
Since its inception more than a decade ago, Sea to Sea has evolved into one of Mexico’s most distinguished trail-running challenges. What began as a small regional project, created by local ultrarunners to showcase the landscapes of the Sierra La Laguna Biosphere Reserve, has grown into an international event known for its rugged terrain, strict environmental standards, and immersive natural experience.
The race was originally conceived to highlight the unique natural corridor linking the Sea of Cortez and the Pacific Ocean, a route once traversed on foot by ranching families and explorers. Today, that historic path forms the backbone of a single, uninterrupted 105-kilometer trail featuring a 2,000-meter elevation gain.
This year’s event maintains the hallmark route that defines the competition. Athletes must complete the course over three days, with two overnight rests inside the Sierra La Laguna Reserve. Participants will cross oak forests, steep ascents, high-altitude ridgelines, and remote ranching communities, terrain known for being both physically demanding and visually stunning.
To improve safety and reduce congestion on narrow mountain trails, organizers have divided the 1,100 runners into two start groups: the Sierra Group, competing from December 4 to 6, and the Mar Group, from December 5 to 7. This system, implemented in 2022, allows for smoother logistics and a better overall experience for participants.
Natalia Ruffo Castaño, director of municipal tourism, said Sea to Sea has become “one of the most successful examples of sport-based tourism in the state,” emphasizing its balance between environmental preservation and economic development. “Events like this position La Paz as a destination for nature and endurance sports while creating real benefits for rural communities,” she said.
This year’s economic impact plan includes direct financial support for San Dionisio and Rancho La Rueda, the communities hosting the official campsites. Residents contribute by offering logistical assistance, cooking, mule support, and trail maintenance, opportunities that generate income during the event and in the weeks leading up to it.
With its blend of wilderness, cultural heritage, and coast-to-coast adventure, Sea to Sea has gained recognition among international trail runners. Recent registration records show growing participation from Europe, South America, and the United States, reflecting Baja California Sur’s rising profile in the global ultrarunning community.
The 2025 edition is expected to build on that momentum, combining world-class competition with sustainable tourism in one of Mexico’s most biodiverse mountain ranges. Among the participants are members of the indigenous Tarahumara community from Mexico’s Sierra Madre Occidental, renowned for their exceptional long-distance endurance.
