Aldeia do Mato Open Water Swimming 2026

The Castelo de Bode reservoir defines the swimming experience here, a massive expanse of deep, still water held by a concrete wall constructed between 1945 and 1951. Swimmers navigating these stages often find the water to be a deep, opaque blue, shifting in tone as the sunlight hits the surrounding hills. Unlike coastal swims, this environment is defined by its stillness, where the lack of tidal currents forces athletes to find their own rhythm across long, steady stretches. The reservoir, serving as a primary node in Portugal’s power grid, provides a vast, enclosed playground where the main challenge is endurance rather than fighting the sea.

Historical echoes on the water

As you sight your next buoy, the landscape offers more than just hills. The Zêzere river valley once served as a strategic frontier during the Reconquista, and the 'Linha do Tejo' defensive network remains visible to those looking toward the shoreline. You might pass the silhouettes of medieval outposts that once guarded these borders. Further downstream, the history turns more tangible; the 1755 Lisbon earthquake, which devastated the capital, also left its mark on the region. The tremors caused significant structural damage to the castle of Abrantes, specifically destroying the upper prison tiers, a reminder of the tectonic instability that shaped this topography. By the 19th century, this area became a staging ground for the Napoleonic forces under General Junot, who utilized the geography of the Tagus valley to maneuver troops, eventually earning the title of Duke of Abrantes for his strategic control of the river corridor.

Race day logistics

The event, organized by Clube Swim4fun, spans three days in June, covering a cumulative 50 km for those attempting the full circuit. With individual stages ranging from 4.5 km to 11 km, the race demands that every swimmer provides their own kayak or boat escort for safety, a necessity given the scale of the reservoir and the distance between the remote river beaches like Isna Velha and Fontes. Registration fees vary from 40 EUR for shorter, single-day challenges to 190 EUR for the full multi-stage competition. Participation includes a souvenir to commemorate the descent through the heart of the Santarém region.