In Hungary, a huge subterranean thermal lake has been discovered below a Turkish bath.

The lake, thought to be one of the biggest in the world was discovered in an underground cave complex, when explorers ventured beneath the baths in the Hungarian capital Budapest.

Szabolcs Leel-Oessy is a geologist.

"It is special because it is active. In the Budapest under the sea, a lot of caves, seven big caves and three dozen smaller ones, together is 40 kilometres long. Sometimes very beautiful precipitations - some aragonite, calcite, barite crystals. But the all other caves are inactive and dry."

Divers have spent the last few weeks exploring the depths of the lake.

The government is now considering opening up the lake to the public.

Hungary was part of the Ottoman Empire in the 17th century and has a legacy of Turkish baths which remain extremely popular with local residents as well as millions of tourists who flood the city.