The Dragon's Hide

The Dragon's Hide (also known as the Dragon Den, Dragon Sanctuary, Dragon Mountain and Valka's Den) is a dragon nest from How to Train Your Dragon 2. It is somewhat a sanctuary for all of the dragons rescued by Valka. The King of Dragons' Hide resides here.

Location
The Dragon's Hide is located far north, many hours away from Berk on dragon-back (days, maybe weeks on boat).

Characteristics
The Dragon Den is a beautiful place full of green rock pillars and light blue water. It has plants growing everywhere, and has cliffs and many waterfalls in it. There are also mountain areas in the Dragon Den, and lots of rivers and deltas. There is also clear white-ish mist all around the den. There are many caverns and holes in the rock pillars and cliffs and other places.

The Dragon Den's climate is unknown, but it seems humid. Note that there are many places in the caverns that have ice in them; it may be cold at the outside but warm at the inside.

Lore
Valka was taken to the Den by Cloudjumper, where she befriended the dragons within and became their protector. There she became enemy to Drago Bludvist and Eret.

Twenty years later, Hiccup and Toothless are found by Valka and her swarm of dragons and taken to the den where he learns of the Bewilderbeast and Valka's history with them. Stoick, Gobber and their dragons follow the scent of Hiccup's helmet to the den where they find both Hiccup and Valka hiding away.

Drago locates the nest and deplotys his army, only for Valka and her army of dragons to fight back. Her bewilderbeast emerges from the mountain, only to be countered by Drago's. His bewilderbeast kills the Alpha, takes control of the other dragons and flies off, leaving the nest barren.

It is assumed that some of the dragons returned after Toothless' victorym though it is unlikely.