The Hawaii County Fire Department said the man in his 60s was mauled around 12:30pm.
He sustained injuries to his hands and back of his left leg in the attack.
He swam to a cameraman moored in the bay, where the vessel’s crew tended to his injuries.
A ski then transported the man to shore, where Hawaii County Fire Department were waiting.
He was treated on scene, before transfer to hospital.
The species behind the attack remains unclear.
A man was seriously injured by a shark at the same spot in December.
Witnesses report the swimmer, in his 60s, was attacked by a 12-foot (3.6-metre) tiger shark and sustained wounds to his hip and buttocks.
That incident came less than a week after a 60-year-old Washington State woman disappeared off South Maui, while snorkelling.
The woman’s husband said he was snorkelling next to her, about 50 metres from Keawakapu Point, in the minutes prior to the attack.
Shark’s dorsal fin ‘zipped back up’ after serious damage
