Kamencové jezero (Alum Lake)

Kamencové jezero, often described in English as Alum Lake, lies on the northern edge of Chomutov and is one of the region's most unusual places to swim. The lake developed in an area once used for alum-shale mining, and its water has a naturally acidic mineral character with a pH of around 3. That chemistry gives the lake its distinctive reputation and makes a summer swim here feel very different from an ordinary pond or outdoor pool.

The atmosphere is relaxed and practical rather than wild: landscaped beaches, changing facilities, water attractions and sports areas make it a full-day summer stop for families, groups and anyone staying near the Ore Mountains foothills.

Swimming and beaches

The water surface covers almost 16 hectares and the lake is about 676 metres long. It is relatively shallow, with a maximum depth of around 4 metres and an average depth of about 2 metres, so the swimming area is friendly for families while still feeling spacious.

Visitors can use sandy and grassy beaches, a floating pier with slides, children's pools, changing cabins and sanitary facilities. The acidic alum water is the main curiosity, but the comfort of the swimming area is what makes people stay for the afternoon.

Sports and activities

The site offers more than swimming. Depending on the season and current operation, you can find:

• Beach volleyball, badminton, football tennis, streetball and table tennis
• Minigolf and adventure golf
• Pedal boats, small boats and paddleboards for hire
• A rope centre for children and adults
• Wakeboarding and water skiing nearby at Velký Otvický rybník

This makes the lake easy to combine with a longer active day in Chomutov, especially with the zoopark, aquapark and historic centre close by.

Admission

Season passes are usually available. Check current prices and seasonal conditions before setting out, especially outside the main summer holiday period.

Practical information

The usual season runs from 1 May to 30 September. Standard opening hours are 9:00-19:00, with reception generally open 8:00-20:00. A typical visit takes 2-4 hours, but the beaches and sports options make a longer stay easy.

Bring swimwear, a towel, sun protection and footwear suitable for a bathing area. The lake is especially good for families, casual swimmers and visitors who want an unusual natural-water experience without giving up basic facilities.

Directions and contacts

• Website: kamencovejezero.cz
• Address: Mostecká 6102, 430 01 Chomutov
• GPS: 50.4710, 13.4228
• Reception: +420 777 187 843
• Gatehouse: +420 734 852 759
• E-mail: recepce@kamencovejezero.cz