Megyer-hegyi Tarn, Protected lake in Sárospatak, Hungary.

The Megyer-hegyi Tarn is a mountain lake nestled in a rock basin with steep walls and clear water about 6 meters deep. Vertical rock walls rising around 70 meters form a natural bowl that cradles the water.

This location served as a quarry from the 15th century until 1907, when miners extracted a volcanic rock called rhyolitic tuff for millstone production. The quarry was eventually abandoned, and the site later became protected.

The miners who worked here left traces of their daily lives carved into the rock face – you can still see unfinished millstones and small shelters carved into the stone. These remnants tell the story of how people once labored and lived at this location.

The lake can be reached on foot from Károlyfalva and Sárospatak; the Malomkő educational trail, marked with a red hiking sign, starts in Sárospatak's centre. The paths total about 1 km and are steep in places, with railings at the former quarry rim for looking down into the basin. Information boards help with orientation, and the area is open all year.

In 2011, readers of the Origo news portal's online game "Star Tour", which sought Hungary's seven natural wonders, voted the Megyer-hegyi Tarn the most beautiful and placed it first. The site covers 1.07 hectares, making it one of Hungary's smallest protected areas.