The "Goofonatilus" was a submarine created by Goofy.
The Goofonatilus was an "upmarine" created by Goofy after Mickey Mouse was banished to the Unreachable Island by the Mayor of Mouseton in order to appease the Phantom Blot. Propelling the wings with his arm movements, Goofy was able to sail across the Pacific Ocean to the Island in no time to rescue Mickey, and swam back before nightfall.
Behind the scenes
The Goofonatilus appeared in Mickey Mouse and the Unreachable Island.