There are a multitude of Unnamed Islands or locations mentioned in various media across the DreamWorks Dragons Franchise.
Two Islands in Legend of the Boneknapper Dragon
In the Movie Short, Legend of the Boneknapper Dragon, Gobber tells the history of his interactions with the then-mythical Boneknapper Dragon. His story grows more and more less credible. At one point in his young adulthood, he relates he is stranded on a very small desert island, equipped only with a broom hand attachment. He needed to get to the neighboring larger island (but still not very big), but a large number of Hammerhead Sharks gather around him. He fights his way across the water, and is further attacked by his Boneknapper. A Hammerhead Whale supposedly saves him at the last moment.
These two small sandy islands appear in Gobber's account to be tropical islands. Both have palm trees, which are native to tropical regions. Also the Hammerhead Shark is typically found in temperate and tropical waters. In theory this would not be feasible in the cold North Atlantic. It is possible that Gobber has traveled elsewhere in the world during his younger years.
Unknown Volcanic Land in Legend of the Boneknapper Dragon
In the Movie Short, Legend of the Boneknapper Dragon, Gobber tells the history of his interactions with the then-mythical Boneknapper Dragon. His story grows more and more less credible. As an adult of perhaps late 20's or 30's, Gobber is being chased by his Boneknapper. He is only equipped with an egg-beater as an attachment for his missing hand. He flees through very dense forests of bamboo, stops to look at a patch of azaleas, then continues to the apex of an active volcano. He is saved by a Hammerhead Yak emerging from the lava of the volcano.
This land or island has a large, cone shaped active volcano, surrounds by lush vegetation of trees and bamboo. There are also azaleas. Neither bamboo or azaleas are native to Scandinavia. In theory this would not be feasible in the cold North Atlantic. It is possible that Gobber has traveled elsewhere in the world during his younger years, as this location has an Eastern Asia 'feel'.
Locations in Dragons: Riders of Berk and Dragons: Defenders of Berk
Unnamed Islands in Dragons: Riders of Berk and Dragons: Defenders of Berk may be viewed HERE
Locations in Dragons: Race to the Edge, Season 1, Season 2, and Season 3
Unnamed Islands in Dragons: Race to the Edge, Seasons 1-3 may be viewed HERE
Locations in Dragons: Race to the Edge, Season 4, Season 5, and Season 6
Unnamed Islands in Dragons: Race to the Edge, Seasons 3-6 may be viewed HERE
Locations in Dragons: Rescue Riders
Unnamed Islands in Dragons: Rescue Riders may be viewed HERE
An unnamed island appears in the companion book To Berk and Beyond in the section called "Survival in the Age of Dragons" when discussing shelter. There is no caption. The section discusses finding shelter when lost in the wild. Timberjacks are mentioned as providing decent shelter when no other is available.
The island also appears on Hiccup's map in How to Train Your Dragon 2, just to the North West of Dragon Island. A different version of this unnamed island appears in the same location on the official Dragons: Race to the Edge map.
In Dragon Down (Comic)
The island has a central, active volcano with hot caverns inside. The combination of stressed Stoker dragon and active volcano means the volcano could erupt.
In Queen of the Hill (Mini-Comic)
In this short story found in the comic The Legend of Ragnarok, Astrid and Stormfly are stranded on an island that isn't named. The island is forested with some beaches and rocky pools. There is a large pit on the island which is easy to fall into. It is also filled with Smothering Smokebreaths.
In The Eel Plague (Mini-Comic)
In this short story found in the Ultimate Dragon Trainer 's Guide magazine, the Dragon Riders search for a Typhoomerang on an unknown island. The island is covered in grass, some of it very tall, and seems to have no tree cover. There appear to be several cliff areas on this island. Typhoomerangs are known to be native to this island.
Locations in Games
Unnamed Islands in Games may be viewed HERE