Six people have drowned off Maui beaches since Jan. 14. 
 
 Six people have drowned off Maui beaches since Jan. 14. 
 
 Over the course of 11 days, 6 people drowned off Maui 
 
 Over the course of 11 days, 6 people drowned off Maui 
 
 Full-face snorkeling masks don't have mouthpieces like conventional snorkels. The mask goes over a person's head. 
 
 It's supposed to offer easy breathing through your nose and mouth and give a swimmer a panoramic view for a better snorkeling experience. 
 
 California visitor Kathie Sylbies bought one for her Hawaii vacation.. 
 
 "You have a wider view and there wasn't the snorkel mouth piece in the way. It was great! I Ioved it!" she said. 
 
 But not everyone is a fan. 
 
 Robert Wintner owns Snorkel Bob's. He designs snorkeling gear. He refuses to sell or rent full-face masks after his team field tested the equipment. 
 
 "These full-face masks are bad for snorkeling," he said. 
 
 MORE: Over the course of 11 days, 6 people drowned off Maui 
 
 Winter said the mask can trap dangerous levels of carbon dioxide as a swimmer exhales, making it difficult to get oxygen. 
 
 "Carbon dioxide buildup is known to lead to what we call a gray feeling," he said. "Some people say it makes them sleepy. We know that it can exacerbate panic, which I think is the big culprit in most of these incidents you are seeing now across Hawaii." 
 
 Recently on Maui, two visitors drowned while wearing full-face snorkels. 
 
 Physician and waterman Dr. Philip Foti is on a state task force studying drowning deaths and equipment associated with ocean accidents.. 
 
 "I think there is too much focus on this full-face mask as a problem. The fact is that this full-face mask is kind of an extreme example of many of the modifications in or on snorkels," he said. 
 
 Foti believes there isn't enough evidence to declare the full-face snorkeling mask more dangerous than other snorkels.. 
 
 But Wintner said the masks often are poorly designed and don't fit snugly. 
 
 "Even a slight movement like squinting can allow water to leak in," he said. 
 
 Visitor Daneen Davinna said a full-face snorkel she tried filled up with water. 
 
 "I felt safer and more comfortable in a regular snorkel," she said. 
 
 Full-face snorkeling masks are sold online and in stores. Some beach activity companies rent them to customers. 
 
 Copyright 2018 Hawaii News Now. All rights reserved. ||||| Nine people have drowned off the coast of Maui over two weeks, a spike of incidents that officials are calling "unprecedented." 
 
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 After two men were pulled from the water Jan. 14, another seven were discovered over the next 13 days. 
 
 Getty Images 
 
 Five of those nine men were snorkeling, which is nearly one-third of the deaths authorities expect to encounter over a full year. 
 
 Drowning is the leading cause of death for tourists in Hawaii, authorities told ABC News. In a typical year, 17 people drown while snorkeling. 
 
 Experts advise all swimmers to know their limits, take frequent breaks and get out of the water if they're at all feeling uncomfortable. Tourists renting equipment and masks also should make sure before embarking that everything fits properly. ||||| Related Headlines 2 Bay Area men die 3 days apart while 
 
 - Another Bay Area man has died off Maui's coast, becoming the ninth drowning victim in that region in two weeks. 
 
 Maui police told KTVU the latest victim has been identified as Alexander Tsukerman, 71, of Berkeley. 
 
 Tsukerman was snorkeling Saturday off Maluaka Beach when he was found floating face-down. 
 
 He was taken to Maui Memorial Medical Center, where he was pronounced dead the following day, according to police. 
 
 Tsukerman's death was the third within a two day period in the waters off Maui. 
 
 Since Jan. 14, there have been nine people who have died while snorkeling or scuba diving along Maui's southern shore. Three of those victims have been from the Bay Area. 
 
 On Jan. 18, 50-year-old Bryan Beyer of Oakland died while snorkeling at Kamaole Beach Park III. 
 
 Two days later, a Castro Valley man died after he was found face-down and unresponsive offshore from that same beach. 
 
 On Tuesday, police told KTVU that victim has been identified as 67-year-old Michael Mellin. 
 
 Emergency response officials in the region called the spike in drowning deaths "unprecedented." 
 
 The deaths have raised concerns about full-face snorkeling masks, according to some local reports. 
 
 Critics say masks that cover the face can trap harmful levels of carbon dioxide and make it difficult for the swimmer to get enough oxygen, Hawaii News Now reported. 
 
 "Some people say it makes them sleepy. We know that it can exacerbate panic, which I think is the big culprit in most of these incidents you are seeing now across Hawaii," snorkel gear retailer Robert Winter told Hawaii News Now. 
 
 Winter, who also designs snorkeling gear, said his team has field tested full-face masks, and he now refuses to rent or sell that type of equipment. 
 
 Fire officials told local news website Maui Now that Tsukerman was not using a full-face mask but was equipped with a traditional two-piece mask and snorkel. 
 
 It's unclear how many of the victims who have died in recent weeks were wearing a full-face mask. ||||| Third East Bay man drowns off Maui beach in 2 weeks 
 
 A third East Bay man has drowned off Maui's beaches, the ninth drowning fatality reported on the Hawaiian island in two weeks. A third East Bay man has drowned off Maui's beaches, the ninth drowning fatality reported on the Hawaiian island in two weeks. Photo: M Swiet Productions/Getty Images Photo: M Swiet Productions/Getty Images Image 1 of / 13 Caption Close Third East Bay man drowns off Maui beach in 2 weeks 1 / 13 Back to Gallery 
 
 A third East Bay man has drowned off Maui's beaches, the ninth drowning fatality reported on the Hawaiian island in two weeks. 
 
 The 71-year-old Berkeley resident was found facedown in the waters off Maluaka Beach in Makena on Saturday, Maui Fire Police Chief Edward Taomoto confirmed. The man was transported to a local hospital in critical condition, where he later died. 
 
 Fire officials said the man was at the beach with family and friends but had set out into the water to snorkel alone. He was wearing a traditional two-piece mask and snorkel. 
 
 The incident follows the recent drownings of two other East Bay residents in Maui's waters – a 67-year-old Castro Valley man and a 50-year-old man whom media identified as Bryan Beyer of Oakland. 
 
 Matt Alley, Beyer's best friend of 30 years, said his friend worked in real estate as a loan adjustor and had great sense of humor. Beyer was vacationing in Maui with his girlfriend of 10 years, Alley added. 
 
 Maui police have yet to release the identities of the Berkeley and Castro Valley victims. Both men were snorkeling off Kamaole Beach Park III, and died two days apart on Jan. 18 and Jan. 20. 
 
 Taomoto said the victims were wearing one-piece, full-face snorkels, a new design that covers one's eyes, nose and mouth. 
 
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 Taomoto said his department has noticed a recent uptick in the number of snorkel-related drownings or near drownings involving the one-piece masks, "but it is too early to make any sort of connection to the use of this equipment and drownings." 
 
 "There is speculation that there may be an unforeseen buildup of carbon dioxide within the breathing chamber in the one-piece, full-face mask design," Taomoto told SFGATE. "If a person were not getting enough oxygen, then it is possible for that person to lose consciousness." 
 
 Hawaii's four counties are currently collecting data on the incidents involving the full-face snorkel design, Taomoto said. 
 
 Since Jan. 14 Maui waters have seen nine snorkeling or scuba diving deaths, including the recent drownings of a 52-year-old man from Saint Paul, Minn. and a 62-year-old man from Salem, Ore. on Friday. 
 
 Taomoto described the series of drownings as an "unprecedented spike" to Maui Now. 
 
 According to data compiled by the Honolulu Civil Beat, drowning is the leading cause of death for tourists in Hawaii. The visitor-drowning rate in Hawaii is 13 times the national average. 
 
 Michelle Robertson is an SFGATE staff writer. Email her at mrobertson@sfchronicle.com or find her on Twitter at @mrobertsonsf.
– Hawaiian authorities are urging swimmers and snorkelers to stay safe after what they describe as an "unprecedented" spike in drownings off the coast of Maui. Nine people, including at least three tourists from California, drowned near several beaches on the island between Jan. 14 and Jan. 27, ABC News reports. All the victims were men, and authorities say five of them drowned while snorkeling—bringing the death toll in the space of two weeks to almost a third of the 17 snorkeling deaths Hawaii experiences in an average year. The drownings have raised concerns about recently introduced models of full-face snorkeling masks, which critics say can trap dangerous levels of carbon dioxide, reports KTVU. "Some people say it makes them sleepy. We know that it can exacerbate panic, which I think is the big culprit in most of these incidents you are seeing now across Hawaii," retailer Robert Winter tells Hawaii News Now. He says that after field-testing the masks, which cover the eyes, nose, and mouth, he refuses to sell them. Maui Fire Police Chief Edward Taomoto says that while it's too early to make a connection to the equipment and the recent rise in drownings, "there is speculation that there may be an unforeseen buildup of carbon dioxide within the breathing chamber in the one-piece, full-face mask design." "If a person were not getting enough oxygen, then it is possible for that person to lose consciousness," he tells the San Francisco Chronicle.