But the number of visitors who drowned increased from 18 in 1999 to 40 last year, a 122 percent increase. That rise dwarfs the 2.5 percent increase in visitors to Hawai'i from 1999 to 2004.

Ocean safety officials and an official with the state Department of Health said that several factors, such as unfamiliarity with local water conditions, pre-existing health conditions, and unsupervised children contributed to the rise in drowning deaths.

"There is an obvious problem with nonresidents being unfamiliar with local conditions and obviously underestimating the ocean environment in Hawai'i," said Dan Galanis, who studies drowning statistics as part of his job with the state Department of Health's injury prevention and control program.

In Hawai'i, 69 people drowned in 1994 and again in 1996, the previous peaks in recent years, according to a state report. Statistics covering the years before 1990 were not immediately available. However, 159 people died just in the Hawai'i tsunami of 1946.

According to the National Center for Injury Prevention and Control, men and children are most likely to drown. In 2001, male victims accounted for 78 percent of drownings in the United States, according to a 2003 Center for Disease Control and Prevention study. The same study showed drowning remains the second-leading cause of injury-related death for children between the ages of 1 to 14.

The age and gender breakdowns were not immediately available for the state figures.

Summer brings big surf to O'ahu's south shores, and the hot, humid weather draws people to beaches and pools. Bad weather, physical exertion and alcohol greatly affect a person's ability to swim, and can be potentially fatal for novice swimmers, especially visitors to the Islands.

Officials say that swallowing your pride and using common sense will help you stay safe.

"People sometimes don't even pay attention when you give them warnings," said Honolulu Fire Department Capt. Kenison Tejada. "They overestimate their ability but underestimate the ocean."

Tejada said people should never swim in a pool or stretch of beach that isn't supervised by a lifeguard. Being in good physical health is another factor to consider before swimming, as is knowing how to swim, he said.

"Parents should supervise their children, that's No. 1," Tejada said. "Here in Hawai'i all children should learn how to swim, as well as their parents."

Two deaths Wednesday showed the danger in pools and the ocean. On that day, a 2-year-old boy and a man died of apparent drownings in separate incidents. Both were local residents.

Police said a Kahalu'u man found his 2-year-old grandson floating in the family's pool at about 7:30 a.m. The boy was taken to the Castle Medical Center, where he was pronounced dead.

The man told police that he last saw the boy playing on the steps of the pool about 15 minutes before he was found.

In the second case, the body of a man was found floating near Pier 51B on Sand Island about 9:50 a.m. Police said the man, identified as a 46-year-old Honolulu resident, had been reported missing.

Officials did not release the name of either victim. Autopsies have yet to be completed.