The Marxa Popular Vall de Siarb begins and ends in Llagunes, a village within the Vall de Siarb, held annually on the last Sunday of May. This event is a popular mountain walk, not a strict race, with routes planned to showcase the valley's landscape. It has a history of at least 20 years, and its Llagunes base provides a close-knit community atmosphere from start to finish.
The route crosses the valley's varied terrain of fields, forests, and historic working paths. Certain years feature restored bridle paths that historically connected villages and grazing areas; other routes may lead towards Soriguera via the Mola path, passing a former flour mill, following the river, winding through the oak grove towards Vilamur, and ascending into the village using the Horts path. Participants encounter expansive valley vistas, shaded sections, moderate ascents and descents, and local historical sites like the Romanesque church in Vilamur. Families participate, with children having the option to join shorter routes, sometimes referred to as marxetes.