The attack happened about 2pm on Saturday while the Sunshine Coast man, 36, was diving off Indian Head on the eastern side of the island.

He suffered a bite to his leg and died from the injury about two-and-a-half hours later, police say.

A doctor and nurse provided first aid to him on shore before paramedics arrived.

Fraser Coast Mayor George Seymour said the local community was deeply saddened by the tragedy.

"This a tremendously sad day for our community," Mr Seymour wrote on Facebook.

"Our deepest condolences go to this young man's family and friends.

"The loss of a young life with his future before him is a tragedy beyond words and we share their sadness and grief."

It is Australia's fourth fatal shark attack this year.

Last month, Gold Coast surfer Rob Pedretti, 60, died after he was mauled by the three-metre white shark at Salt Beach at South Kingscliff in northern NSW.

A shark also killed 23-year-old Queensland wildlife ranger Zachary Robba in April off North West Island in the southern Great Barrier Reef.

Experienced diver Gary Johnson, 57, was killed by a shark near Cull Island in Esperance on Western Australia's south coast in January.

A report will be prepared for the coroner.

Australian Associated Press