Breakneck Bog

S1 E17: When Trader Johann doesn't show up as planned, Stoick becomes concerned – Johann is carrying a very important item for him. Hiccup and the kids find Johann floating by himself in the middle of the ocean, saying he got too close to Breakneck Bog, where his ship was enveloped by a mysterious fog. The kids venture into the bog to retrieve Johann’s ship, despite the legends of a deadly fog monster than inhabits the island.