Two people are dead after a helicopter crashed off Hamilton Island this afternoon.

The helicopter, which was a Whitsunday Air Services aircraft, crashed into the water 250 metres from the Hardy Reef pontoon.

Four passengers and one crew member were onboard the chopper when it went down.

The helicopter was coming into land at the Hardy Reef Heliport. (File/Chris Holmes) (Supplied)

An aerial view of Hardy Reef, home to the Heart Reef, in the Great Barrier Reef. (Image: AAP) (AAP)

Whitsunday Air Services said the accident occurred while the helicopter was on final approach for a landing at the heliport.

Emergency services were working on two people who subsequently died.

The three others were able to extricate themselves; one has serious injuries and two have minor injuries.

(9NEWS)

"We are extremely saddened by this incident and our deepest condolences are with the families of all of the passengers," Whitsunday Air Services said in a statement.