The dead pilot whales were photographed during the trip on Thursday over a beach at Longufjorur.
It's unclear how the mammals became beached. The region where they were spotted is secluded, inaccessible by car and has very few visitors.
Police in the nearby town of Stykkisholmur have been made aware of the discovery, local media say.
The images were taken by helicopter pilot David Schwarzhans.
Edda Elisabet Magnusdottir, a marine biologist and whale expert, told Iceland Monitor that when such mammals enter shallow waters "most of them have a tendency to become disorientated".
She added that pilot whales usually swim in tight groups, which is why so many of them become stranded at once.
Half of the whales had died by the time they were discovered, while the remaining were put down as it would have been too difficult to save them.
