Dolphin Quest are awaiting the results of a post mortem after the mysterious death of three-year old Heydon.

He was found dead in the pool he shares with the three other dolphins at their base in Dockyard's maritime museum on Tuesday.

Dolphin Quest general manager Christine Mihelcic said the death had been a shock.

"He's such a young age and was a healthy and vibrant individual."

She said there were no marks on his body or suspicions of foul play.

Bermudian doctor Dr. Ian Walker from the Baltimore Aquarium, who happened to be on the Island, performed a six-hour necropsy on Heydon assisted by Dolphin Quest Supervisor of Marine Animals Roma Hayward.

Ms Mihelcic said there were no initial theories on what might have caused the death. Samples will have to be sent overseas and she could not say when the results would be in.

Fun-loving Heydon had made his mark in his short time and was even environmentally aware, said Ms Mihelcic.

"If anyone dropped a pamphlet into the pool he would get them out."

Heydon, named after the oldest chapel on Bermuda, located in Somerset, was lovingly known as the most vocal of all the dolphin family and his curious nature guaranteed he would be at the front of the crowd investigating any new goings-on, said Ms Mihelcic.

"Caliban and Heydon shared a close mother-son relationship and he was definitely known as a 'momma's boy'.

"His energetic and playful spirit made him profoundly loved by all the staff and trainers, and promoted a strong connection with guests who had the privilege of meeting him face-to-face.

"It is understandable the trainers and staff are absolutely devastated and shocked by the loss of such a beloved family member."

She said the three other Dockyard dolphins were adjusting to new circumstances but there was no scientific evidence that they were capable of mourning.

She said the average life span of a dolphin was 30.