The lake occupies a quarry that ceased operations during the 20th century.
The distinctive turquoise color of the water is caused by mineral content and sunlight reflection against the deep basin.
The geological composition is predominantly andesite, a volcanic rock typical of the Mátra region.
The surrounding cliffs provide nesting grounds for several protected bird species.
Széles-kő is a former andesite quarry located near the village of Apc in the Mátra foothills of Hungary. The site features a deep, cliff-enclosed turquoise lake formed by groundwater filling the abandoned excavation pit. The surrounding rock faces reach significant heights, creating a natural amphitheater effect around the water. The area is a protected natural value recognized for its unique geological formation and microclimate. While the lake was once used for bathing, access for swimming is restricted due to safety concerns regarding underwater obstacles and steep cliffs. Visitors can observe the distinct stratified layers of the volcanic rock face from the elevated vantage points surrounding the basin.
The highest point of the southern rim provides the best panoramic view of the lake surface against the rock walls.
Wear hiking shoes with good grip, as the paths around the rim are unpaved and can be slippery.
Bring a camera with a wide-angle lens to capture the height of the cliffs and the scale of the lake.
Stay on the designated trails as the cliff edges are unstable and steep.
Do not attempt to swim in the lake, as the water depth is inconsistent and the quarry contains submerged industrial debris.
Open year-round, but trails may be difficult to navigate following heavy rain or snow.
Respect local environmental signage and do not leave any waste; the site is a sensitive natural area.
