
With their beautiful rock formations, crystal lined chambers and colourful landscapes, these are the secret caves that run for 40 miles under south Wales.

The images were captured by photographer Brendan Marris, who has extensively explored the Welsh caves system, exploring places few have ventured to go.

Mr Marris often descends underground with his camera to shoot the secret landscape below.

One of the underground caves below south Wales which have been captured on camera by photographer Brendan Marris

The Ogof Ffynnon Taf cave, one of the longest in south Wales, which is also known as the Lesser Garth cave

A caver stands underneath the rock formations of the Ogof Craig a Ffynnon cave, which was first discovered by persistent digging in 1976

The part of the Agen Allwedd cave known as the Turkey Streamway. This particular cave is known as a habitat for bats

And now he is sharing his stunning images, which show the secret vast chambers and amazing natural mazes.

Mr Marris says he has been a caver all his life and was inspired to start taking pictures on his adventures to try and replicate the images he saw in caving guidebooks.

But despite caving all over the UK, the underground chambers of south Wales remain his favourite location, due to their largely unexplored nature.

The main chamber of the Saddle Head cave, which is known for its beautiful rock formation within it

The Selenite tunnel of the Ogof Ffynnon Ddu cave, which is one of the most extensive and complex to explore in the whole system

The unusual rock features in the Ogof Draenen cave, which is one of the laegest cave systems in the country

He told his flickr blog: 'Last year on a visit to Dan Yr Ogof we decided not to follow the main passage into the massive chambers that mark the end to the cave but to break off before this point and explore a rarely visited branch passage.

'By avoiding the allure of the Great Hall at the end of the cave, we entered a smaller but stunningly beautiful passage, overlooked by virtually all cavers who are drawn to see the chambers at the end of the cave.'

Mr Marris adds that caving can be quite a safe pastime if all the proper precautions are taken and can be very rewarding as he gets to see largely hidden landscapes.

A caver crawls through the narrow passages of the Ogof Y Ci cave, which has a number of dry passages

The Piccadilly waterfall below ground in the Cwm Dwr Quarry cave, which is full of maze like passages

A caver climbs up the slab squeeze in the Ogof Foel Fawr cave, one of the shorter chambers of the south Wales underground system

He explained: 'Many people imagine caving as lots of tight crawls and squeezes, thinking it could hold little attraction.

'And if that was all there was, it would be very true — but beyond, lies open passages, deep pits, high vaulted chambers, and streams that meander through the hillside.

'The challenge is to find the route, overcome the obstacles, and follow the passages deep into the mountains to reveal the secrets held within.'