The Flying Christine will be the star attraction of a St John Seafront Sunday on 30 June.
In November 2024 the Flying Christine will be 30 years old.
This is its design life and it was not foreseen it would still be in service beyond 2024.
To continue to use it, Guernsey's Ambulance Service have had it refitted.
Communications officer Jim Cathcart says people will be able to go on board at a St John Seafront Sunday at the end of June:
"It's a rare opportunity, so we're hoping to kick off the anniversary by allowing people to come on board and see what is a unique life saving asset for the Bailiwick of Guernsey."
He says visitors will see how a dedicated marine ambulance is designed and fitted out:
"If you look inside it looks very much like the back of a road ambulance, with a stretcher, a clinical treatment area and an area for the paramedics to sit."
Jim Cathcart says Guernsey's Ambulance Service is indebted to the crew of the Flying Christine:
"It's crewed by volunteers from the local marine community and we couldn't run that lifeline service without them. It's an opportunity to come and meet them and help us celebrate 30 years."
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