第11回 うどん県さぬきオープンウォータースイムレース

On the morning of the Sanuki Open Water Swim, the coastline of Tsuda awakens to the rhythmic movement of swimmers gathering at the water's edge. Organized by the Japan International Open Water Swimming Association, this annual event brings together a dedicated community of athletes who return to these waters year after year. The atmosphere is defined by the collaborative spirit of the JIOWSA, which manages the logistics to ensure safe passage through the coastal currents of the Seto Inland Sea.

The coastal backdrop

As you sight your line, you will find yourself swimming alongside the Tsuda no Matsubara, a sprawling pine grove of 3,000 trees. These ancient sentinels, some reaching 600 years in age, create a distinct acoustic environment; locals often say the wind whistling through the needles mimics the delicate resonance of a koto. Beneath the surface and extending onto the nearby land, the region holds deep archaeological significance. You are swimming in the shadow of the Tsuda Kofun cluster, a collection of ancient burial mounds that mark this area as a site of profound historical weight. Further inland within Sanuki city, the Tomita Chausuyama Kofun stands as the largest burial mound in the entire Shikoku region, a silent witness to the early Kofun period that has overlooked this coast since the mid-5th century.

Navigating the Seto Inland Sea

The race takes place within the geography of the Seto Inland Sea, the vital waterway that separates the island of Shikoku from Honshu. This ecosystem is characterized by its sheltered channels and proximity to Shodoshima, the second-largest island in the sea. The organization of the swim relies on meticulous planning to navigate the tidal behavior typical of this inland environment. Swimmers are encouraged to utilize the official resources provided by the association, including the OWS handbook and technical guidance, to prepare for the specific water conditions found in Sanuki. With the next edition scheduled for July 19, 2026, participants have the opportunity to engage with one of the most historically layered stretches of water in Japan, where every stroke is framed by ancient tumuli and the enduring legacy of the coastal pine groves.