The dangers of tombstoning - jumping into the sea from heights - is to be spelled out to young people in Devon.
A waterfront safety event is being held in Plymouth with free entertainment to encourage more under-18s to attend.
Police have organised the multi-agency event at Commercial Wharf on Friday to tackle the problem of tombstoning.
"The summer holidays attract tombstoners, often with disastrous results when a jump has gone wrong," Pc Mark Hodges said.
In June, coastguards said a group of teenagers continued to tombstone off Plymouth Hoe, despite seeing one of their friends taken to hospital on a spinal board after being seriously injured.
"We've organised this event to educate these youths about the real dangers they face when jumping into unknown waters," the officer added.
Practical advice on understanding tides will be given, along with the general dangers of the waterfront.
Plymouth Community Safety Partnership, Plymouth City Council, Devon and Somerset Fire & Rescue, the RNLI, Plymouth Harbourmaster and the Maritime and Coastguard Agency are all been involved in the event.
City councillor Joan Watkins said having worked as a casualty nurse she was more than aware of how life-threatening and life limiting tombstoning can be.
"It horrifies me to see children undertaking this risk-taking behaviour and we must drive home the message that tombstoning is just not worth it," she said.
The event, which runs from 1600 BST until 2000 BST at Commercial Wharf, will include dance workshops, a skate park and music.