Scuttlebutt Island

Scuttlebutt Island is an island located on Lake Gravity Falls. It is said to be where The Gobblewonker lives, and a colony of beavers make their home here, although Dipper, Mabel, and Soos ruin their Gobblewonker-shaped shelter after accidently crashing into it when being chased by the Gobblewonker.

History
Dipper, Mabel, and Soos came there in search of the Gobblewonker. The sign post for Scuttlebutt Island was used by Soos as a joke to Mabel, making the island's name seem like if it were "Butt Island" instead of its original name. The three of them traveled through the island to find the Gobblewonker.

Believing they had found the creature, they made ready to capture it on film, however, it was a colony of beavers, with the mysterious sound they heard being made by a beaver toying with a chainsaw. Dipper, feeling discouraged, sits on a rock, but the rock turns out to be the Gobblewonker and moves, making Dipper fall in the water. The Gobblewonker then chases them through the island and the lake.

Scuttlebutt Island is seen again in "Fight Fighters" albeit in a pixelated form.

Trivia

 * "Scuttlebutt" in slang usage means rumor or gossip, deriving from the nautical term for the cask used to serve water (or, later, a water fountain).
 * Scuttlebutt Island was originally named "Sasparilla Island."