Fishing Season: Opening Day

 is the first day of fishing season in Gravity Falls, Oregon. It first appeared in "The Legend of the Gobblewonker," when Grunkle Stan took Dipper and Mabel fishing. Evidently, the event is special to the community of Gravity Falls.

History
may have been an event happening annually in Gravity Falls. It is unknown for how long this has been running. There is some evidence that Grunkle Stan attends the opening day every year, and fishes alone. In "The Legend of the Gobblewonker," Stan takes Mabel and Dipper to Lake Gravity Falls (where the opening day was taking place). There the twins heard of the Gobblewonker, and decided to ditch Stan to find it. They were later disappointed to discover that Old Man McGucket had created a replica of the creature to get his son's attention. The twins and Soos rejoined with Stan to go fishing. The group took many photos, and spent the rest of the day on the lake. Fishing Season: Opening Day also appeared in "The Time Traveler's Pig."

Trivia

 * Many recurring characters appeared at the Opening Day; including Lazy Susan, Manly Dan, Tyler, and Toby Determined.