Buttertubs potholes, karstic erosion at Buttertubs Pass, between Wensleydale and Swaledale, Yorkshire Dales National Park, Yorkshire, England, United Kingdom, Europe

Buttertubs potholes, karstic erosion at Buttertubs Pass, between Wensleydale and Swaledale, Yorkshire Dales National Park, Yorkshire, England, United Kingdom, Europe

A caver in Valley Entrance, Kingsdale, Yorkshire Dales, Yorkshire, England, United Kingdom, Europe

A caver in a tight squeeze in the Yorkshire Dales, England, United Kingdom, Europe

A man exploring the old abandoned Coniston copper mines in the Lake District, Cumbria, England, United Kingdom, Europe

Cavers in County Pot in the Yorkshire Dales, Yorkshire, England, United Kingdom, Europe

A caver in the Yorkshire Dales, Yorkshire, England, United Kingdom, Europe

Birdhouse made with a pot and an hollow branch

Waterfall and Pot hole in rock outcrop, River Orchy, Allt Broighleachan, Argyll, Scotland

Waterfall and Pot hole in rock outcrop, River Orchy, Allt Broighleachan, Argyll, Scotland