Thrill-seeking youngsters hurling themselves into the sea face serious injury or even death, the RNLI has warned.

Dozens of teenagers could be seen on Monday (May 7) jumping off the Albion Groyne on Brighton beach into the sea in a dangerous practice called tombstoning.

When The Argus visited, the teenagers could be seen doing back-flips and somersaults into the shallow water below, watched by friends.

Alexis Vivas, 38, who was fishing with his young daughter, said the youths were setting a poor example for other children.

Mr Vivas, of Elm Grove, Brighton, said: “I don’t think it is a good example for younger children watching them jump off the groyne when everyone is here.

“I was here 20 minutes ago and I even saw someone jump off Brighton Palace Pier and I find that very dangerous.”

Another resident Donald, who did not want to give his surname, said: “I have seen a few boys doing it.

“But it doesn’t matter, you put a sign up and say it is prohibited but they will still ignore it.

“It is not safe.”

The youths were jumping into the water despite the sea being only 10C, a temperature at which people are advised to wear wetsuits if they go in the water, and lifeguards not being posted on the beach until the end of the month.

Tombstoning is particularly dangerous as water depth can be unpredictable and alter with the tides.

The water may be shallower than the jumpers think and there are often hidden objects on the seabed.

Other dangers include the shock of cold water and unanticipated currents.

In the UK there have been at least 20 fatalities since 2005.

Father-of-three Vincent Wagstaff died after asking his cousin to film him leaping off a sea wall in Plymouth, Devon, in October 2016.

A video shown at his inquest showed the horrific moment he misjudged the jump from the 33ft wall before he died from multiple injuries.

An RNLI spokesman said: “We realise that it’s tempting to jump from height into the water, especially with such great weather but submerged items may not be visible and could cause serious injury if you hit them.

“The shock of cold water may also make it difficult to swim and in some places strong currents might sweep you away.

“A safer alternative is coasteering with a registered coasteering provider able to give you the necessary training and equipment.

“Coasteering involves exploring the coast by rock-hopping, shore-scrambling, cave-exploring and cliff-jumping.”