24-hodinovka

Noon marks the start of a day-and-night swimming odyssey in the clear inland water of Nové Košariská. Known formally as 24-hodinovka – festival vytrvalostného plávania v otvorenej vode and widely called simply 24-hodinovka, this is an open water swimming endurance marathon held in the lake basin of Areál jazera Nové Košariská in Dunajská Lužná, near Bratislava in Slovakia. Swimmers plunge into the lake at midday on Saturday and keep moving through the afternoon, the dark hours of the night, and the morning until the clock marks a full twenty-four hours. Maintaining strokes across a full diurnal cycle requires a well-supported camp along the lakefront. Swimmers are monitored by official water rescue crews, active timekeeping teams, and course referees to log every circuit safely through the dark.

To keep bodies fueled across twenty-four hours in the water, the event provides participants with one breakfast and two hot meals between their shifts. The gathering was first held in June 2021 at Veľké jazero Rovinka. Following that initial edition, the marathon transferred in 2022 and 2023 to Nové Košariská in Dunajská Lužná, where it found its natural venue under the local swimming club Ľadové Medvede Veľká voda. Pushing through the full cycle is an extreme challenge that tests muscular stamina as well as psychological resilience.

Nové Košariská: crystal depths of the former gravel pit

Nové Košariská began as an industrial excavation site, carved out by gravel extraction operations during the 1970s. The water in Nové Košariská lake is remarkably clear, maintaining a degree of purity that closely approaches drinking quality. Because the lake was dug out for gravel, the bottom drops away precipitously right beside the bank. Swimmers leave the shallows and immediately find themselves floating over depths reaching up to 40 meters, making the basin a renowned training spot for deep divers. Looking down through the glass-like water into that indigo void provides an extraordinary sensation of flying in open space. A small peninsula extends into the water, dividing the lake into two distinct sections.

One basin stays shallower and is shaded by trees along its banks, while the main body opens toward wider expanses. Entering the swim is straightforward from the eastern shoreline, where a broad gravel beach provides clean, stable footing into the shallows. Other segments of the waterfront are lined with private recreational cottages that preserve a quiet, residential atmosphere along the perimeter.

Beneath the surface: fish and jellyfish of Nové Košariská

Carp, northern pike, and wels catfish inhabit the lake, while small freshwater jellyfish occasionally drift through the water during the autumn months. The wels catfish prefers large, warm lakes and deep waters, spending its daylight hours concealed in sunken bed holes or nestled near submerged logs. Along the margins, the northern pike functions as an ambush hunter in shallow, weed-filled pockets of lakes and slow-flowing waterways. On sunny summer days, pike stay tucked away within dense beds of shoreline vegetation, venturing into more open water only when heavy winds ripple the surface. Swimmers following an open water line across deep water stay well outside their weed-sheltered hunting lanes. Swimmers who visit in the autumn may encounter freshwater jellyfish, delicate creatures measuring just 20 to 25 millimeters across. While they use tiny stinging cells to capture microscopic aquatic prey, these cells lack the strength to pierce human skin, leaving them entirely harmless to swimmers sharing the water.

Hrušov reservoir and the bird sanctuaries of Vtáčí ostrov

About five kilometres from Nové Košariská lies the Hrušov wetland, an ecological expanse of almost 500 hectares overseen by the Danube Floodplains Protected Landscape Area Administration. The wetland is celebrated for its natural standing waters that host vibrant communities of floating and submerged aquatic plants. These sheltered channels provide rich riverine habitat for the European beaver and support amphibians such as the European fire-bellied toad. Within the nearby Hrušov reservoir, roughly three kilometres from the swimming area, lies Vtáčí ostrov. Covering less than seven hectares, this artificial sanctuary was constructed to offset the floodplain forests submerged during the development of the Gabčíkovo-Nagymaros waterworks. The island now serves as a key refuge for wetland waterfowl within the Danube floodplains.

Vtáčí ostrov hosts unique bird colonies: it is the only nesting ground in Slovakia for the Mediterranean gull, and the sole breeding outpost in western Slovakia for the common redshank. To preserve this sanctuary, the island remains strictly off-limits to visitors during nesting, migratory, and wintering seasons.

Benkove ostrovy and the wild Danube floodplains

Each islet is shaped from gravel into a low, rocky strip measuring roughly 50 meters long and 10 meters wide, rising just one to two meters above the surface. During the breeding months, little ringed plovers, wagtails, and mallards congregate along these stony banks.