Olsztyn has eleven lakes within its city limits, and Lake Ukiel — also called Krzywe Lake — is the biggest and best loved. A municipal beach with sand and lifeguards opens in summer on the eastern shore, with a sailing club just along from it. A flat, well-marked footpath circles the whole lake — about 10 km — through pine forest.
In winter the lake freezes; on cold January weekends locals come out for ice fishing and skating. The bus from the centre takes 15 minutes; rented bikes get you here from the old town in 20.