Scuttlebutt Island

Scuttlebutt Island is an island located in Lake Gravity Falls. It is said to be where the Gobblewonker lives, and a colony of beavers make their home here, though Dipper, Mabel, and Soos ruin their Gobblewonker-shaped shelter after accidentally crashing into it with a boat while being chased by the Gobblewonker.

History
In "The Legend of the Gobblewonker," Dipper, Mabel, and Soos go 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 as if it were "Butt Island" ( Scuttle butt island) instead of its original name, by covering the "Scuttle" part with his arm. The three of them continued to travel through the island to try and find the legendary 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 monster-like sound they heard being a beaver toying with a chainsaw. Dipper, feeling discouraged, sat on a rock, but the rock turned out to be part of the Gobblewonker and moved, making Dipper fall in the water. The Gobblewonker then chased them through the island and the lake.

Scuttlebutt Island is seen again during the credits of "Fight Fighters," when the town is in a pixelated form.

In "Dreamscaperers," the island is seen again on the lake, at the beginning of the episode when the town of Gravity Falls is seen from above.

In "Gideon Rises," Scuttlebutt Island is seen on the lake in the multiple overhead views of the town.

In "Scary-oke" when Agent Trigger and Agent Powers turn on a satellite view on the screen in The Government Base, Scuttlebutt Island can be seen again.

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 going to be named "Sasparilla Island."