All the fatalities were male tourists, aged between 50 and 67 and all but one from other US states.
Most of the deaths occurred off beaches on the south-west coast, although in one of the two most recent cases, both on 26 January, a 52-year-old was snorkelling from a tourist boat. The other, 62, was snorkelling near a beach.
Two days earlier, on 24 January, a 57-year-old scuba-diver who had been solo-diving for about an hour was spotted by two freedivers lying on the seabed at a depth of 3m some 30m from shore.
On 22 January another scuba-diver, a 66-year-old Canadian, died while swimming back to shore following a dive with a family-member.
On 20 January, a 67-year-old who had been snorkelling with friends drowned close to shore, and two days before that a snorkeller of 50 died in similar circumstances. Both these men are believed to have been wearing full-face snorkelling masks, devices that have generated some controversy in Hawaii.
The masks, which have no mouthpiece, have been claimed to allow a dangerous build-up of carbon dioxide to occur, or to be prone to sudden leakage of water that can cause panic in the wearer.
In all the incidents, bystanders and rescue services attempted unsuccessfully to revive the victims.
According to Maui Fire Department, which has coastguarding responsibilities on the island, all the incidents took place in calm conditions on what are considered to be safe beaches.
Hawaii as a whole typically sees about 60 drownings at sea each year.
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