The rescue helicopter was launched today when a diver suffered from the bends as he came to the surface of the water off Unst.
The 35-year-old was diving from the six-metre rib Clive Dive at the Bluemull Sound north east of Snabrough when the morning incident happened.
A link-call was arranged to allow the patient to talk to hospital doctors in Aberdeen, where a hyperbaric chamber is kept. Medical staff advised he be flown south for treatment.
The patient was taken to Uyeasound, and the coastguard helicopter was scrambled from its Sumburgh base to attend the scene.
A team of coastguard volunteers based in Baltasound also attended the scene and provided assistance for the helicopter.
On Tuesday a diver was airlifted to hospital after suffering from a suspected case of the bends as she surfaced from the water off the Knab.
The Sumburgh-based rescue helicopter was scrambled when the alarm was raised at around 11am . She had been diving off the Valkyrie.
The helicopter flew her to Kirkwall, which is equipped with a hyperbaric chamber.