The RNLI last night issued a warning about the thrill-seeking craze for jumping from a height into water, also known as gravity chasing, after it emerged Laurence Parrott, 17, from Errogie, near Inverness, was thought to have been performing high jumps with friends into the pool at the foot of the 165ft Falls of Foyers which feed into Loch Ness.

Despite a two-day search there has still been no trace of the teenager.

It was not clear whether he plunged in the water near the spot, or fell further down the steep drop before the alarm was raised just before 5pm on Sunday.

But an RNLI source said it was believed the youths had been there for recreational reasons, to jump in and out of the water “from a considerable height”.

The source said: “It was a pleasant day and the water is incredibly powerful, a dramatic piece of water and the pool that forms at the bottom, I am sure, would have been very attractive,” said an RNLI source.

“What is not clear is whether it was as a result of climbing out and falling backwards in. Tombstoning is not something we encourage because of the extreme nature of the activity, and it could have desperate consequences.”

A Northern Constabulary spokeswoman said: “There will be no comment on this tonight. The family have asked to be left alone.”

Some adrenalin junkies were last month criticised for posting a video of their tombstoning tour of Scotland which gave out a map of jump sites from Perthshire, through the Highlands and Banffshire.

Labour justice spokesman Richard Baker called for action to curb the “Jackass culture” around Scotland’s coastline as police warned teenagers they were risking their lives by tombstoning. Another video posted online showed a teenager jumping 100ft off Arbroath’s cliffs.

Tombstoning, although not illegal, has claimed at least 12 lives in the UK in the past few years.

According to figures from the Royal Society for the Prevention of Accidents (RoSPA), 1200 people have been admitted to hospital in Britain in the past five years as a result of injuries.

In July, Stuart MacDonald, 27, from Aberdeen was killed after jumping from a pier at Findochty harbour, Moray, and in June 19-year-old Joel Scott died after tombstoning 40ft from a cliff in Yorkshire and landing on rocks below.

In May this year, 17-year-old Jamie Sutton died after jumping 30ft into the sea in Whitburn in Tyne and Wear.

The Maritime and Coastguard Agency which has warned of the dangers, saying it is hard to judge the depth of water due to swell and river or sea conditions, has been working in partnership with the RNLI and RoSPA to tackle the problem through educational initiatives.

Last night Laurence’s parents said in a tribute to their son in a statement released by Northern Constabulary: “Laurence was full of life and was very determined, excelling at everything he put his mind to. We cannot put into words the loss that we feel and would ask that our family be left alone to grieve in peace.”

Laurence attended Stratherrick Primary and Inverness Royal Academy, where he excelled in music.