A WOMAN who was cave diving in the Clydach Gorge died when her air cylinders ran out of oxygen.

Experienced diver Bonnie Cotier, 53, was visiting the area on April 23 this year from her home in St Neots, Cambridgeshire to dive the Pwll y Cwm caves along with South and Mid Wales Cave Rescue co-ordinators, Martyn Farr and Duncan Price.

The inquest into her death at Newport Coroners' Court heard Ms Cotier, originally from Washington DC and her husband, Stephen Francis Houbin, had shared a passion for diving which took them to France, Mexico and the US.

Both had attended courses and attained qualifications to international diving standard.

Mr Houbin, who was not able to attend the dive due to work commitments, told the inquest he had no concerns about the dive but rather the drive to and from the site.

Mr Farr, a diver with 40 years experience who in the capacity as a professional scuba diver instructor met Ms Cotier while attending a meeting in Yorkshire and arranged for her to accompany Mr Price on his research dive at the Pwll y Cwm Caves.

The aim of the dive was to enable Mr Price to take photos in a restriction in the cave about 15 meters in.

Mr Farr explained to the court how guide ropes were placed 25 meters inside the cave to deter inexperienced divers from entering and that their cylinders had enough oxygen for a 45 minute dive.

He said at first the dive had proceeded to plan, the photos were taken of Mr Price inside the restriction and Ms Cotier acted as a photography assistant staying near the entrance.

Once the photo was taken, Mr Price went further into the cave to continue his research while Mr Farr returned to the restriction to install a guide line from the entrance to a permanent guide line to enable Ms Cotier to go through the restriction and have a look around the cave.

Mr Farr said he only realised all was not well when Ms Cotier failed to surface some 42 minutes into the dive.

Despite running low on oxygen, Mr Farr returned to the cave and found Ms Cotier alive and well a short way from the main guideline.

He caught her by her harness and quietly moved her forward but Ms Cotier suddenly broke away from him going in the wrong direction.

Mr Farr was then forced to return to the surface and summon assistance from his partner who brought him oxygen from his house six miles away and called the emergency services.

After reaching the surface Mr Price re-entered the cave and found Ms Cotier's body.

When he checked her two seven litre cylinders for oxygen he found them both to be empty.

A member of the cave rescue team, Mr Price told the inquest he has dived well over 200 times at Pwll y Cwm and at first everything was going according to plan. He only knew something was wrong when he resurfaced.

On finding Ms Cotier, Mr Price said she was hanging vertically in the water, her regulators were not in her mouth, both cylinders were empty and diving line was around her waist.

Mr Price said it wasn't part of the permanent line but suggested that it was the reel that had been taken through the restriction. He added that the line around Ms Cotier's waist had not hindered her progress but suggested she would have had to cut the line to free herself.

Pathologist Dr Geraint Evans concluded that Ms Cotier died as a result of drowning.

Summing up, Gwent Coroner, David Bowen said, "On the evidence I have heard the intended dive was within Ms Cotier's capabilities.

"In accordance with international diving practice they were not connected to each other with guide rope."

He said that Ms Cotier had become disorientated as to where the exit was.

"There is no suggestion she died due to equipment malfunction or injury. Cave diving mostly carries an element of risk. Ms Cotier became disoriented and ran out of oxygen."

Verdict: Accidental death.