A man who died in an accident at a Gloucestershire diving centre on Monday has been named as Edwin John Girvan of Laleham, Middlesex.
The centre was closed while police and safety experts investigated
The Gloucester coroner, Alan Crickmore, was told the 44-year-old died from asphyxia, and not drowning.
Mr Girvan was the third person to die at the flooded former quarry at Tidenham, near Lydney in six weeks.
The coroner formally opened an inquest after being told Mr Girvan had been identified by his wife.
In April, a Berkshire couple in their 20s drowned while diving in the lake.
In the latest accident 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.