Calders Geo is UK’s ‘biggest cave

A sea cave in Eshaness has been judged the biggest in Britain by a local geologist, providing a welcome boost for Shetland’s already well-regarded status as a geological wonderland.

Calders Geo has been measured at an “absolutely enormous” 5,600 square metres.

That is almost double the size of Frozen Deep in Somerset’s Cheddar Gorge, which has held the accolade until now.

The claim has been made by geologist Jonathan Swale.

He used a laser range-finder to help carry out his measurements, which are expected to be verified by a visiting cave expert next month.

Mr Swale began thinking about Eshaness after his research found promising results in Papa Stour.

“I’ve known about the cave for a long while, and when Shetland became a geopark we were doing a bit of research into the size and length of caves elsewhere.

“It occurred to me that the Eshaness cave might be a big one.

“I went in about a month ago, and kayaked in with a friend’s range-finder that he used for shooting and just took a few distances across the cave.

“I came back and plotted it on paper and found it’s absolutely enormous. So I thought I’d better go back and do a bit more of a detailed survey.”
Mr Swale returned to the cave this week. This time he gathered more accurate results by sitting in a fixed position on rocks rather than from a boat.

“I scanned around the cave, 360 degrees, firing at points on the rock and getting compass bearings, and then plotted that on paper again and got a rough size for it.

“In the mean time I’d been looking at, currently, the largest found cave in Britain, which is a chamber underneath Cheddar Gorge called Frozen Deep.

“That one has a floor area of about 3,000 square metres. I thought the Eshaness one was a bit bigger than that. And it turns out it’s nearly twice as big. My survey shows about 5,600 square metres.”

The discovery could spark a welcome reaction from visitors to the isles, although access is clearly restricted to those able to travel by kayak. Mr Swale said it was already attracting interest in the kayaking community.

And his reaction? “I’m delighted. I was going to say it puts Shetland on the map, but we’re already there. It just sticks on a great big exclamation mark.”