Trou Saint-Martin (Hole of Saint-Martin) is located on the top of the mountain of La Barre des Dourbes at 1700 meters in altitude near the town of Dignes-les-Bains in Alpes de Haute-Provence department of France. The arch is accessible by a marked trail via Pas de Tartonne (escarped hiking pass) on 2 hours. The hike begins at the forest house of Serre on the hamlet of Les Dourbes. The opening has a measured span about 5.0 meters and a height of 4.0 meters.