A man died during a dive at a flooded quarry because he did not switch on his breathing apparatus, an inquest heard.
Mr Girvan ran out of oxygen during a dive at a quarry in Tidenham
Edwin Girvan, 44, of Laleham, west London, died of asphyxia at the National Diving Centre at Tidenham, Gloucestershire, on 24 May 2004.
The Gloucester inquest heard that Mr Girvan, an experienced diver, was trying out new diving equipment with two friends at the dive site.
The inquest recorded a verdict of accidental death.
On the day of the accident the trio had planned to dive 50 metres to the bottom of the former quarry.
Friend Nick Gilbert said he and Edina Ochert, from Buckinghamshire, saw Mr Girvan go though the normal safety checks before the dive.
Mr Girvan switched off his diving equipment to preserve the battery while he waited for his diving companions.
They joined him in the water several minutes later, but Mr Girvan failed to switch the equipment back on again and ran out of oxygen after 10 metres.
He then dropped to the bottom of the lake.