Loki Island

"I've managed to locate wood on Loki Island that's lighter and stronger than anything we've ever seen!"

- Stoick the Vast to Hiccup

Loki Island is an island that is only mentioned by not seen in the movie short, Dawn of the Dragon Racers.

Geography
Based solely on Stoick's statement above, Loki Island is large enough to support old-growth forests suitable for timber to build a ship.

Dawn of the Dragon Racers
Berk's Regatta celebration, or Ship racing, is approaching. Chief Stoick has heard of special timber found on Loki Island that is light and strong, and would make a good Viking Longship to race. He indicates the journey by ship to Loki Island will take "a couple of days". In the meantime, Stoick puts a young Hiccup in charge of Berk and setting up for the Regatta.

Trivia

 * There is a tree mentioned in the Franchise called the Loki Tree; it is possible that this is the tree that Stoick is looking for.