The Hungarian capital is home to over 80 geothermal springs. As this naturally heated water flowed deep below the Earth’s surface, it carved out hundreds of caves, making Budapest home to the largest collection of thermal caves in the world.

Molnár János Cave, part of the Buda thermal karst cave system, is featured in the video below. It was named after János Molnár, the first to explore the cave back in 1856 to analyse the water’s chemical consistency.

Divers have charted more than four miles of tunnels since the 1950s, much remains to be explored and enjoyed. Relatively recently a MJ cave dive centre opened with the aim of offering a,

"Well equipped dive center with comfortable facitilites to ensure an awesome dive experience in this unique underwater cave system in the heart of Budapest".

This dive centre team say, "We welcome all certified cave divers who would like to see the wonders of the Molnár János cave."

"Diving is special in the Molnár János cave because the water is warm (20-28 Celsius degrees) all year round and crystal clear, and there are exciting stone and crystal formations on the limestone walls. There are no strong currents within the cave, the water flows very slowly."

The 'Great Big Story' video below was made in partnership with the Hungarian Tourism Agency.