Two divers were taken to hospital after a rescue operation off Bressay on Monday afternoon.
The coastguard was called to assist following a call of an incident involving the diving vessel Valhalla.
One diver was airlifted to the Gilbert Bain Hospital by the coastguard helicopter while another was taken ashore by the vessel and transported by ambulance.
Police Scotland received a report of two divers in difficulty off the island of Bressay at around 4.30pm. Enquiries are at an early stage.
The Maritime and Coastguard Agency said: “A diver has been taken to hospital after being reported by a diving vessel to be in difficulty.
“The diver was winched aboard the HM Coastguard helicopter from Sumburgh which was in the area on exercise and taken to the Gilbert Bain Hospital.
“After the diving vessel returned to Lerwick and was met by Lerwick Coastguard Rescue Team, a second diver was passed into the care of the Scottish Ambulance. We have no further information.”