The Marble Arch Caves show how spectacular the world can be below ground. The 7.1 mile (11.5 km) long limestone caves are the longest in Northern Ireland and are considered to be among the most spectacular in Britain. The mystical caves are formed by three rivers that flow off the Cuilcagh mountain and meet underground, forming the Cladagh.
The caves are part of a UNESCO Geopark where you can learn about the area's geological heritage. The region is also rich in cultural heritage – humans have inhabited these dramatic landscapes for over 7,000 years.
Tickets, which include a guided tour, are £10 for adults and £5 for children. Concessions and 60+ pay £7.50.