Sharks launched 79 unprovoked attacks on humans in 2010, the highest number in a decade, US researchers have found.
Six people died from unprovoked attacks, up from an average of 4.3 over the past 10 years, University of Florida scientists said.
Thirty-two attacks occurred in North American waters, 14 off Australia and eight in South African waters.
Scientists say reported attacks have risen over the past century as humans spend more leisure time in the water.
The 2010 figure was up from 63 in 2009, and above the yearly average over the past decade of 63.5.
"But the rate of attacks is not necessarily going up - population is rising and the interest in aquatic recreation grows," University of Florida ichthyologist George Burgess said in a statement announcing the university's international shark attack report.
"That will continue as population rises."
Size and power
Vietnam and Egypt each suffered six unprovoked shark attacks. The situation in Egypt was unusual in that five attacks, one of them fatal, occurred within five days, researchers said.
In the US, the state of Florida again had the most attacks, with 13, but that represented a fourth straight year of decline from a high of 31 for the state in 2007.
The researchers recommend that if a person is attacked by a shark, he or she should strike the shark on the nose, distracting the creature, then flee the water.
"If this is not possible, repeat bangs to the snout may offer temporary restraint, but the result likely become increasingly less effective," Mr Burgess reported.
"If a shark actually bites, we suggest clawing at its eyes and gills, two sensitive areas. One should not act passively if under attack - sharks respect size and power."
Humans kill 30 million to 70 million sharks per year in fisheries, the researchers said.