A recent rash of drownings off the coast of Maui, three of them being victims from the Bay Area, has prompted officials to launch an investigation into full-faced snorkel masks.
At least two of the nine people who drowned over a 13-day stretch were wearing the gear.
While an official cause of death has not been determined, the mask's design is raising some safety concerns.
Heidi Williams, the girlfriend of 50 year old Bryan Beyer of Oakland who drowned last week in the waters at Kamaole Beach Park III, told KTVU her boyfriend was an experienced swimmer and one-time lifeguard.
She said she is contemplating legal action against the maker of the full-face snorkel mask that Beyer was wearing when he died. On social media, Williams has indicated that Beyer was not snorkeling alone.
"I was there with him although I was not beside him," she wrote in the comments section of a recent article in 'The Maui News.' "[I am] still confused as to how this happened. The cause of death is drowning."
Critics of the recently popular full-face snorkel mask say it creates carbon dioxide buildup which can cause some to become disoriented or lose consciousness.
"The person that gets this is the person that's not comfortable in the water," said Mark Stanley, the owner of Bamboo Reef Dive Centers in San Francisco. Stanley said mostly beginners who buy the mask, which has been on store shelves for about two to three years now.
Stanley admits more tests need to be done on the mask, but he says it's beginner snorkelers are more prone to panic or hyperventilate in the water.
"You're breathing really hard but you feel that you're not getting the breath," he said, while demonstrating how the mask operates. "So, it's more I think related to the individual and their anxiety and such rather than the exact design of the mask itself. It's also possible to have carbon dioxide buildup with a regular snorkel mask as well."
Snorkeling is the leading cause of death for tourists in Hawaii. According to its State Department of Health, between 2007 and 2016, 156 visitors died while snorkeling, that's an average of 17 deaths a year.
So nine snorkeling deaths in just 13 days has Maui Fire officials calling this "an unprecedented spike" in ocean drowning incidents. They're taking a closer look at the full-face masks.
Hawaii's State Department of Health says most snorkeling drowning victims are men in their 50s and 60s and more than 40 percent have heart conditions.
Autopsies on the victims are still pending. For now, Hawaii officials are reminding tourists to swim in pairs, know their physical limitations and be mindful of currents.