Lake Czos in Mrągowo

Lake Czos is a narrow, deep ribbon lake that lies entirely within the town limits of Mrągowo – together with the Four Winds Peninsula. From the market square you reach the shore in a few minutes, and a promenade leads on to the beaches, the pier and the amphitheatre that has hosted the Piknik Country festival since 1983. Come for a swim in summer, a walk at any time of year, or a stop on the way to Mikołajki.

The lake in numbers

Czos covers about 2.79 km², is up to 5 km long and 0.4 to 1 km wide, and reaches a maximum depth of 43.3 m. It has two arms: a narrower western one (about 3.5 km) and a wider eastern one (about 1.5 km), separated by a high peninsula. At its base rises the twin-peaked Four Winds Hill (183.1 and 165.4 m above sea level), and a small ski area operates on the slopes of the lower, northern summit. The eastern shore is high and hilly, the western one low and mostly treeless. The Dajna river links Czos with lakes Wierzbowskie, Czarne, Kot and Juno.

History: the town began on an island

According to an old tradition, the first settlement stood on an island in Lake Czos – today the Ostrów Peninsula. Excavations by archaeologists from the University of Königsberg, cut short by the Second World War, confirmed the legend. Before 1945 the lake was called Schoss-See in German, and the town Sensburg. In 1889 a municipal gasworks was built north of Czos, supplying gas for street lighting and the barracks.

Beaches, promenade and pier

• Town beach on Jaszczurcza Góra street – a large jetty, playground, sports pitches, toilets and food outlets; the bathing area is split into zones for swimmers and non-swimmers.
• Beach on Osiedle Grunwaldzkie – quieter, with a jetty and a separate children's area; next to it a cyclists' rest stop with a lookout tower, shelter and toilets.
• Promenade – a paved walkway from the Osiedle Grunwaldzkie beach to beyond the amphitheatre on Jaszczurcza Góra; a pier links the lake with John Paul II Square in the centre.

Both beaches have lifeguards only in the summer season. Outside it you swim without supervision.

The amphitheatre and Piknik Country

The lakeside amphitheatre was built in the 1980s, and in 2011–2012 a new venue replaced it. It is the stage for Piknik Country, the Masurian Cabaret Night and the Borderlands Culture Festival. In 2026 it hosted the jubilee 45th edition of Piknik Country (24–25 July), with a gala concert looking back on the festival's history. Tickets for amphitheatre concerts are sold by the Mrągowo Culture Centre at Warszawska 26.

Tripto tips

• Time needed: a walk along the promenade with a break on the pier takes about 1.5 hours; set aside an afternoon for a beach day.
• When: during Piknik Country on the last weekend of July the town is busy and accommodation is scarce – book early.
• Off season: the shore and promenade are open all year, but rentals and supervised beaches are seasonal.
• Nearby: Mikołajki and Lake Śniardwy, the Krutynia canoe trail, and in Mrągowo itself the Museum of the Mrągowo Region.