The Trail Marines Vell is a 21 km mountain race with a positive elevation gain of 1180 meters, held in Marines, Valencia. The course runs along trails and dirt roads, offering a demanding and technical route typical of mountain races in the Sierra Calderona. Participants will encounter varied terrain including narrow singletrack and forest tracks, with sections passing through military areas that are usually restricted but accessible with explicit permission on race day, adding a unique element to the course. The organization provides aid stations with drinks and food, medical assistance, shower facilities, and a runner's bag, along with chip timing. Cut-off times will be enforced at aid stations, and strict rules regarding withdrawal and disqualification are in place to ensure safety and the proper conduct of the event. The race is notable for its natural setting and the distinctive feature of traversing military zones, making it a unique experience for mountain runners.