Trail da Lagoa is a September trail race held at Parque Desportivo de Airão São João in Guimarães, Portugal. Participants can select the 20 km Trail Longo or the 12 km Mini Trail, and there is a non-competitive 8 km Caminhada for walkers. Grupo Desportivo de Airão organizes the event, which follows a morning schedule: the longer race begins first, followed by the shorter trail, and then the walk.
The course crosses mountain trails, rural paths, and natural areas surrounding Airão São João, with the start and finish located at the sports park. Approximately 650 participants are permitted: 250 for the 20 km race, 250 for the 12 km race, and 150 for the walk. The 20 km course has a 4-hour time limit, the 12 km course allows 3 hours 30 minutes, and the walk allows 3 hours. This setup accommodates trail runners seeking a concise local challenge and individuals wishing to participate without competing.