An inquest has been told a lack of planning, experience and essential equipment contributed to the deaths of two divers at a lake in Auckland.
Qualified divers Tyron North and Daniel Stoneham failed to surface during a 39-metre dive at Lake Pupuke on the North Shore in July last year.
Constable Geoffrey Bray from the Police National Dive Squad gave evidence on Tuesday.
Mr Bray said Tyron North was found tangled in rope in soft mud and could not get himself free as he was not carrying a knife or cutters, while Daniel Stoneham was stuck in the lake bed.
Mr Bray said both men were carrying too much weight and did not have experience to dive in a black out.
He also told the inquest there were shortcomings in how the dive was planned and carried out, saying it was dangerous because the divers had the ability to exceed the planned 39 metres.
The men drowned at a depth of 54 metres.
Brian Keith was Mr Stoneham's dive buddy and told the inquest things went horribly wrong shortly into the dive after the group of eight broke up. Some did not follow instructions and started to descend fast.
Mr Keith said the group had joked about sharing a bottle of vodka as a reward for completing the dive and forming a club, but denied they were racing to get to the scheduled depth of 39 metres.
Coroner George Matenga has reserved his findings.
Clifford Stoneham told Radio New Zealand on Tuesday that mistakes were made and someone should be held responsible for his son's death.
Mr Stoneham said the deaths were preventable and does not blame the group's dive instructor, but hoped he has learnt valuable lessons.