Teenagers have been seen leaping into the sea from a tower at a harbour in Orkney.

Police have warned the youths they could be risking their lives as the water around the navigation towers at Pole Star Pier in Stromness is shallow.

The activity, known as tombstoning, caused the deaths of 20 people in the UK between 2005 and 2015, and injured 83 others.

The teenagers were seen at Pole Star Pier on Tuesday evening.

A Police Scotland spokesman said: "The tower itself is not safe to climb as there are a number of cables and pieces of equipment attached to it.

"Tombstoning is considered to be life-threatening and dangerous behaviour as it can be very hard to judge the depth of water due to swell and sea conditions.

"Serious injuries - or worse - can result from hitting an underwater obstruction."

He added: "Following an inspection of the nav tower it appears that equipment on the tower has been damaged.

"Police would like to speak to any of the 'teenagers' involved in climbing the tower or from any persons who may have witnessed this incident."