Savonlinnan halkiuinti

Koululahti bay cuts directly into the island-strewn heart of Savonlinna, where Lake Saimaa narrows into rushing blue straits. Savonlinnan halkiuinti is an open water swimming race held in the freshwater expanse of Lake Saimaa in Savonlinna, in the region of Etelä-Savo, Finland. Swimmers assemble on the Kasinonsaari island shoreline of Koululahti bay, gathering near the historic wooden villa Suruton before stepping down into the clear northern water. Wading in from the beach, the atmosphere is informal and welcoming, with participants eyeing the calm stretch of the inlet ahead. The swim traces a straight line across the sheltered bay for approximately 800 meters, linking the island bank directly to the urban townscape opposite.

Organised by Savonlinnan uimaseura ry in late July, the event welcomes swimmers of various experience levels, requiring parental consent for anyone under eighteen. Wetsuits are permitted in the lake, and the organizers advise using a tow float for added visibility and safety on the open water. Slicing through the freshwater, you navigate an uncomplicated sprint where the urban shoreline remains in steady view with every stroke. The finish line sits right at the wooden landing pier of Panimoravintola Huvila, a brewery restaurant perched directly on the waterfront. Swimmers touch the dock and pull themselves out of the lake straight onto the sunlit deck, transitioning in seconds from swimming to post-race socializing.

Olavinlinna: Erik Axelsson Tott's fortress in the Kyrönsalmi current

Less than a kilometre from the race course in Koululahti, the monumental fortress of Olavinlinna rises dramatically from a rocky islet. Construction of the castle began in 1475 under the direction of Erik Axelsson Tott, giving birth to the settlement of Savonlinna on the western shore of the strait. The site was chosen specifically for its hostile aquatic geography: completely surrounded by water, the ferocious natural current of the Kyrönsalmi passage kept the surface from freezing over in winter, creating an impassable moat. While those fierce flows barred invaders, the race itself stays safely sheltered in the tranquil waters of nearby Koululahti bay. Sieges across the centuries turned the surrounding water into a battleground; in 1788, garrison defenders had to construct a covered water passage within the castle walls because snipers were shooting soldiers sent out to fetch drinking water. Three years later, in 1791, the castle's massive round tower, known as Paksu torni, was completely destroyed when its gunpowder magazine blew up. Today, the atmosphere around the ramparts is peaceful rather than embattled.

Lake Saimaa: the interconnected basins of Haapavesi and Pihlajavesi

The waters under your goggles belong to Lake Saimaa, the largest lake in Finland and the fourth largest in all of Europe. This sprawling freshwater labyrinth spans approximately 4,300 square kilometers, bordered by an astonishing 14,850 kilometers of shoreline and sprinkled with some 13,700 islands. The entire lake network drains eastward through the Vuoksi River into Lake Ladoga, which then empties via the Neva River into the Gulf of Finland. The town center of Savonlinna is built directly across the rocky islands that separate two massive constituent basins: Haukivesi and Haapavesi to the north, and Pihlajavesi to the south. Connecting these giant lake bodies are three narrow straits—Laitaatsalmi, Haapasalmi, and Kyrönsalmi—which channel the flow from north to south.

Because the lake is composed of multiple sub-basins connected by these bottlenecks, the currents push water levels in the most distant reaches between five and eleven centimeters apart. Feeding this system from the north is Haapavesi, an eleven-kilometer-long lake sitting at an altitude of 75.8 meters above sea level with distinctively rocky shores. As the southernmost pocket of the Haukivesi system, Haapavesi empties directly into Pihlajavesi through the narrows, giving Savonlinna its restless, vibrant aquatic character.

Koululahti seafront: steamships, spa shores, and summer piers

The urban bay of Koululahti has a long tradition as a local bathing ground, having hosted a popular swimming spot in the 1950s near a high rock cliff by the mouth of the Lötjösen canal. It sits right alongside the town's historic transport heart, where the Savonlinna railway station lines the waterfront and the Kauppatori market stop once carried the name of Koululahti itself. The downtown passenger port maintains 365 meters of quay at a depth of 2.4 meters. This harbor serves as the home base for the region's historic white-sided steamships. Beyond the passenger quays, Savonlinna buzzes with boating life during the warmer months, operating several guest marinas for visiting vessels at Casino, Haislahti, Törninpyörä, and Savonranta. Yachts and day cruisers slip between the islands, sharing the sparkling blue water that surrounds the town on every side.