Kenneth, also known as Ross, McCrimmon, 44, and Rose Bassett, 48, lost their lives in the incident at Little Loch Broom, Wester Ross on Monday.
Emergency services were called to the scene on the A832 at Little Loch Broom in Wester Ross at around 3.45pm.
Coastguards also responded to the incident near Ardessie.
Local councillor Derek MacLeod said workers raised the alarm after seeing the car leave the road.
He said: “There is a nearby fish farm and some of the fish farm workers spotted it, it was about 100 yards from where they were.
“The two people had lived in the Poolewe area for a long time and both worked at Inverewe Gardens.
“Everyone is shocked, it is a small community of people who know each other for many miles around.”
Carol-Ann Boyter, from the National Trust for Scotland which manages the garden, said: “We are deeply saddened by this tragic news. Rose and Ross both contributed a huge amount to Inverewe Garden over the years.
“We are working to support their colleagues at this difficult time and send sincere condolences to their families.”
Police are appealing for information.
Road policing sergeant Gregor Hay said: “Our thoughts are with the family of the two people who have died at this sad time.
“Enquiries into this incident remain ongoing and we would ask that anyone who witnessed the collision or who saw a red Honda Civic travelling in the area at the time to contact police on 101 quoting incident number NE2595/18.”
A Police Scotland spokesman said: “Our thoughts are with their families at this difficult time.
“Inquiries into the incident remain ongoing.