Dragon Hunter Island was a port for the Dragon Hunters.
A major port for the dragon trade. Where Hunters will sell the dragons they have captured for a large sum.
Dragons: Race to the Edge
The Chief of the Dragon Hunters, Viggo Grimborn, and his brother Ryker, had their base on this island when the sold off their captured dragons or faced trouble from Berk's Dragon Riders under Hiccup Haddock III. Ryker then brought in Dagur, his sister Heather, and his Berserkers to the island to meet with Viggo.
The Dragon Riders head for the island to rescue Heather, with Viggo having set up challenges for them to get through. Heather was about to be executed for treason, but a reformed Dagur rescued her and Windshear.
Viggo and his hunters then attempted to make a dragon-proof fortress out of marble on the island. However, Hiccup's riders were able use a pair of Catastrophic Quakens to demolish the fortress.
Despite that setback, Viggo then decided to hold a Dragon Auction. However, the auction was interrupted and ended by Hiccup's riders.