The aircraft with two people on board was spotted in difficulty near Evanton in Ross-shire just after 2pm on Saturday and it then crashed into the Cromarty Firth.
The UK Coastguard was alerted and requested the launch of the RNLI Invergordon lifeboat. The Coastguard rescue helicopter from Inverness was scrambled and the Inverness, Cromarty and Portmahomack Coastguard Rescue Teams were sent to the scene.
The lifeboat launched its inflatable rescue craft and rescued the two people. They were airlifted by the Coastguard helicopter and taken to hospital.
Calum Christie, of the UK Coastguard, said: “Although shocked and hypothermic, the crew were uninjured. It was fortunate that they were spotted by the other aircraft who quickly reported their predicament.
“We were able to get rescue resources on scene swiftly resulting in a positive outcome.”
Last year, a flock of sheep forced a microlight pilot to crash after they wandered on to a runway during his take-off.
The 43-year-old man was moments from lift-off at East Fortune Airfield when several sheep jumped over a fence from their field and crossed the runway ahead of him.
He aborted the take-off and hit the brakes, managing to pass through the middle of the flock without hitting any.
As the runway was coming to an end, he turned off the engine and the microlight crashed into a concrete roof truss that had been placed across the end of the runway.
The incident was reported to the Air Accidents Investigation Branch (AAIB) by the pilot and details were published in its latest bulletin.
It said the weather was good in the area and another pilot had made a successful take-off just two minutes before the accident.
The report said the owner of the land around the airfield had now decided not to keep sheep near the runway.
The pilot got out of the aircraft without difficulty and suffered only minor injuries.