Mountain bike fanatics take note: the Costa Rican race some say is among the toughest in the world, the Ruta de los Conquistadores, starts today and runs through Saturday.

The race course spans from coast to coast, starting in the central Pacific beach town of Jacó and ending in the Caribbean port of Limón. The route has been modified this year to make it more difficult and adhere more closely to the route taken across Costa Rica by Spanish settlers, hence the name.

The race has traditionally been broken into three segments: from Jacó to Ciudad Colón, southwest of San José; from Tres Ríos, east of San José, to the Caribbean slope town of Turrialba; and from Turrialba to Limón.

This year's course has been changed to include the stretch between Ciudad Colón and Tres Ríos that was previously omitted. This new segment runs from Ciudad Colón through the nearby towns of Alto de Quitirrisí, Mora, Acosta, San Ignacio, Aserrí, Guatuso and Quebradilla de Cartago to end in Tres Ríos for a total of 78 kilometers and a 3,000 meter accumulated incline, the statement said.

The entire Ruta de los Conquistadores course measures 350 kilometers and a 12,000 meter climb.

In its 15 th year, the race was started by Tico cyclist Román Urbina.

“I wanted to organize an expedition to retrace the route of the Spanish conquerors in Costa Rica from 1540 to 1560. Who would have imagined that idea would turn into what many call the hardest race on the planet?” Urbina said in a statement from the race's organizers.

Among promising contenders this year are Ticos Federico Ramírez, Deiber Esquivel, Paolo Montoya and Manuel Prado as well as Thomas Dietsch, from France, and Andreas Hestler, from Canada.

Women top contenders include Costa Rican Alejandra Carvajal and Susan Haywood and Louise Kobin, both from the United States.