People have been warned against the dangers of tombstoning after three were seriously hurt jumping 70ft (21m) from a cliff on Dorset’s Jurassic Coast.
The casualties were taken to hospital following the incident at Durdle Door at about 16:00 BST on Saturday.
Lulworth Coastguard Rescue Team said four people jumped from the arch into the sea at the famous beauty spot, egged on by crowds.
“We couldn’t discourage it enough”, the coastguard said.
People have been urged to stay away from Dorset’s beaches and roads around the area have been closed for safety reasons, the council said.
One of the casualties had to be pulled from the sea bed. Another jumped from the arch but managed to stagger back to friends before falling “very unwell”.
Both were airlifted to the major trauma centre in Southampton.
A third person had serious injuries to his body and was taken by ambulance to Dorset County Hospital, Dorchester.
The ages and gender of those involved has not been disclosed.
Lulworth Coastguard Rescue Team said: “We understand that four individuals jumped from Durdle Door (some 70ft) yesterday, encouraged by the crowds on the beach.
“Upsetting scenes like we and many others witnessed yesterday illustrate how very dangerous tombstoning is.”
On Sunday Dorset Council said it had closed the roads to Lulworth and Durdle Door on safety grounds.
The road to West Bexington in West Dorset had also been closed due to “health and safety issues”.
Dorset Council’s corporate director, Jonathan Mair, said: “We would ask people to please think twice before visiting Dorset’s beaches as they are becoming overcrowded, and maintaining social distancing is becoming difficult.”
The area has seen large numbers of visitors during the recent hot weather after lockdown restrictions were eased.