Gaping Gill: Inside as Yorkshire Dales cave opened to the public

The Gaping Gill system is one of Britain's longest and most complex cave systems

People have been given a rare chance to descend into one of the largest underground cave chambers in Britain.

Gaping Gill has a network of tunnels at the bottom of a large crater on the moors near Ingleborough, in the Yorkshire Dales National Park.

The main shaft is about 365ft (111m) deep, which is the same height as St Paul's Cathedral.

Descents into the main chamber happen twice a year, when pothole clubs set up a winch over the main shaft entrance.

Twice a year people are offered the opportunity to be lowered to the bottom of the cave chamber

Many visitors return year after year to be lowered to the cave bottom, according to Bradford Pothole Club

Gaping Gill is one of the most famous caves in the Dales.

Its main chamber measures 423ft (129m) long, 101ft (31m) high, and 82ft (25m) wide and connects to one of the UK's longest and most complex cave systems.

John Birbeck from Settle attempted the first descent in 1842, when he was lowered on a rope by farm labourers.

However he only reached a ledge 190ft (58m) down, according to the Yorkshire Dales National Park.

As well as the main shaft the cave system has 19 other entrances

All the cave entrances unite underground and the water running through the caves eventually emerges into daylight at Ingleborough Cave

The authority said the first full descent to the bottom was made in 1895 by Frenchman Edouard Martel, who used a rope ladder and a candle and kept in contact with the surface by telephone.

Nowadays members of the public can descend to the main chamber twice a year when the Bradford and Craven pothole clubs set up a winch.

The Bradford Pothole Club, which ran the week-long event, has held a Winch Meet at the site for more than 60 years, allowing members of the public and non-cavers the chance to visit the underground scene.

The club's website said the cavern was floodlit, which allowed "the public and cavers alike a view not normally seen outside winch meets".

The week-long event run by Bradford and Craven pothole clubs takes place twice a year