The owners of Jethou Island have donated £10,000 to St John Ambulance in Guernsey.
The Ogden Trust has given the money to support the marine ambulance, the Flying Christine III.
It celebrated its 25th anniversary last November, having been a vital lifeline service for the other islands of the Bailiwick and vessels in local waters.
The vessel, which is staffed by a paramedic led team from the emergency ambulance and crewed by volunteers, is based in St Peter Port Harbour.
It is designed to cut through waves rather than ride on the surface of the sea in order to give patients as smooth a ride as possible.