16. Biserov plavalni maraton in DP 5km OWS 2026

In 1958, the coastal town of Portorož became the global epicenter of chess, hosting a historic international tournament where a young Bobby Fischer secured his grandmaster title at the age of 15. This legacy of precision and endurance resonates today in the spirit of the Biserov Maraton, an annual 5km swimming event that draws athletes to the very waters that have shaped the Istrian coastline for centuries. As you prepare to start from the Jadralni klub Pirat, you are entering a basin with a rich maritime narrative, far removed from the static board of a chess match.

Navigating the Bay of Roses

The bay itself holds the name Portorož, derived from the 13th-century 'Portus Sanctae Mariae de Rosa', named for a church that once stood by the shore. While the physical structure of the sanctuary has long surrendered to time, the calm, shallow waters of this sub-Mediterranean microclimate remain a constant for swimmers. During the race in early September, you can expect the sea to retain the warmth of the summer heat, often reaching temperatures near 25°C, providing a comfortable environment for the 5km distance. Along the course, you will glide past the remnants of the Bernardin monastery, a 1452 construction later fortified by the Austrian military in 1830 to command the Bay of Piran. Look toward the coastline and you may spot the lingering bell tower, a silent sentinel that remains one of the few visible markers of the area's strategic history.

History Beneath the Surface

As you push through the final kilometers, the shoreline reveals more than just modern tourist infrastructure. Near the old salt warehouses in the Fizine district, the water hides the submerged foundations of a Roman-era port and an ancient fish farm, silent witnesses to centuries of maritime trade. The area was once a hub for 1920s hydroplane aviation, with hangars that previously connected these shores to Venice and Turin. For those looking to maintain their rhythm across the season, this race offers a technical challenge distinct from the earlier Sunrise Swim Portoroz, held in June, or the upcoming Mini Maraton Koper in September. Whether you are navigating the swells near the Beli Križ ridge or marking your pace by the Radio Capodistria antenna, the Biserov Maraton provides a direct connection to the deep, layered history of the Slovenian coast.