Running out of air, holding on to weights and catch all factors in diver deaths
Inexperience, poor conditions, heavy weights, and running out of air are all suspected as factors in a spate of diving deaths this summer.
A husband is mourning the loss of his wife in the eighth diving death in New Zealand waters over the warmer months.
The Wellington mother was scuba diving around Island Bay snorkel trail in good weather conditions on Monday afternoon.
Police could not yet say for certain what caused the 37-year-old to get into trouble about 40 minutes into the dive with her husband.
He spotted her in distress near the surface and managed to bring her to shore, ditching gear as he went, police national dive squad head Senior Sergeant Bruce Adams said.
Bystanders tried to resuscitate her, but neither they nor paramedics succeeded.
All four people who died off Wellington's south coast this summer were scuba divers with varying degrees of experience, whose deaths were not yet fully understood, Adams said.
"There's certainly no one thing going wrong in any of these cases."
However, there were common factors among the tragedies from which others could learn, he said.
Running out of air was one common theme, as was divers being weighed down with catch bags they had clipped to themselves.
"We're seeing a lot of fatalities with the diver still having their weight belt on," Adams said.
If people got into trouble underwater, they should not be afraid of ditching expensive gear to resurface at a safe rate. "You are dealing with your own life, your own well-being."
Overestimating ability, misreading the conditions, and not keeping up training could lead to people getting into serious trouble.
Adams recommended regular medical assessments, joining a dive club, going out on the water with a buddy, and studying the conditions.
Divers should also not be over-reliant on dive computers, should check their gear often, and practise emergency manoeuvres, he said.
The official holiday drowning toll was the highest in six years, with six deaths over the Christmas period.
There were three underwater deaths in 2014, and four the previous year.
The popularity and accessibility of the sport, bringing more people into the water, might partly explain the number of deaths this season, Adams said.
"With the water being so good – it's been a great year – I think people are getting out on the water and doing more, and not just diving."
New Zealand Underwater Association diver safety spokesman Mike Torr expressed condolences to the families of all those who had lost their lives diving recently.
"As underwater lovers these really touch us," he said.
He recommended getting a medical every five years, servicing equipment every two years, diving with buddies, and using flags.