Officials did not immediately release the men's names but said they were 22 and 28 years old. The shark severed one man's right foot and then circled back and mauled the other's right calf, Queensland state Ambulance Service spokeswoman Tracey Eastwick reported.
They were brought 11 kilometers (7 miles) by boat to the mainland town of Airlie Beach where paramedics were waiting for them, an ambulance official said. They were then flown by helicopter to a hospital in the city of Mackay in serious but stable condition, RACQ CQ Rescue said.
"An English tourist has had his foot bitten off and another has serious lacerations to his lower leg after a shark attack in the Whitsundays today," the helicopter rescue service said in a statement. The victims told the helicopter crew "they were wrestling and thrashing about in the water" in a passage between Hayman and Whitsunday Islands when they were attacked, the statement said.
A shark killed a man in November last year in a Whitsunday Island harbor where two tourists had been mauled a month earlier. The 33-year-old victim had been diving from a paddle board while on a yacht cruise.
The spate of attacks in the Whitsundays left authorities struggling to explain an apparent escalation in danger in the internationally renowned vacation destination. In September last year, two Australian tourists were mauled on consecutive days, including a 12-year-old girl who lost a leg.