Béka-tó (Frog Lake) is a small natural pool on the south-western side of János-hegy, located on the walking trail from the upper station of the Libegő Chairlift to Jánoshegyi station on the Children’s Railway. This is the largest body of standing water in the Buda Hills. Its presence is extraordinary, as the hills are mainly comprised of limestone which rarely allows for standing water. It exists thanks to a thick bed of clay which does not allow the water to seep away.
Besides the frogs which give the pool its name, there are spotted newts, a variety of water snails and many insects.
The dragonflies that visit Normafa spend their larval stage in this pool and return to it to fill it with their eggs.
The reeds that grow in the area around the pool are sustained by water overflowing from the pool and flowing down from the hillsides.
There are benches, a table, and a fireplace near the pool for visitors to use.