Mossdale Caverns, a cave system in the Yoredale limestone, is ranked amongst the most severe test of caving skills in Britain. Much of the system involves both crawling and squeezing along narrow passages that flood completely after even small amounts of rain.
On the morning of June 24th 1967 a party of ten cavers entered the system. About three hours later four of these gave up, unable to proceed any further into it. When one of these four returned a short time afterwards she found that the entrance was submerged and therefore knew that those inside were in great danger. She immediately set off to run the four kilometres across the moor to raise the alarm.
The flooding prevented the rescuers gaining immediate access and they had to divert the stream away from the cave entrance. Even then the rescue operation could not be started owing to the high internal water levels.
It was not until the following day that entry was possible, the team eventually finding five of the bodies in the Far Marathon Crawls. The sixth was located the following day.
The coroner decided to seal the cave, and concrete was poured down the only safe entrance. Entry, though, was always possible via the stream sink. In 1971 the dead cavers were buried in "High Level Mud Caverns", with the agreement of their families, but kept quiet from officialdom. The safer 'sealed' entrance was opened up in about 1976.
This remains the worst tragedy in British caving. A small metal tablet is now affixed to the rocks alongside the old entrance bearing the following legend
IN EVERLASTING MEMORY
FROM THE FAMILIES OF
GEOFFREY WARREN BOIREAU
MICHAEL JOHN RYAN
COLIN RICHARD VICKERS
WHO REST HERE IN MOSSDALE CAVERNS
WHERE THEY DIED
24th JUNE 1967
I will lift up mine eyes unto the hills
From whence cometh my strength
The caves lie towards the upper reaches of Mossdale Beck approximately 5km north of Grassington.