A man has died at the National Diving Centre in Gloucestershire - the third death in six weeks.
Three people were involved in an incident at the flooded quarry
His body was found in the centre - a flooded former quarry - at Tidenham, near Lydney on Monday. The coroner has been informed.
The diver is believed to be in his 40s and from Middlesex. He was one of three involved in an incident at the centre.
In April a Berkshire couple in their 20s drowned while diving in the lake.
In this latest incident, a second man, from Buckinghamshire, was taken by a Coastguard helicopter to a decompression unit in Poole.
A woman, also from Buckinghamshire, was involved but escaped serious injury.
The alarm was raised just after 1400 BST on Monday when the ambulance service and coastguard were called to the site.
Janine Davison-Evans, 27, of Stockton on Tees, Cleveland, and her boyfriend Hank Austin, 25, of Ascot, Berkshire, both drowned while diving in the lake on Good Friday.