A Island That Moves Around the Map!
Could appear or disappear out of no where, or maybe it submerges from under the water and pops up because its on the back of a sea animal (Turtle, Crab, Fish, etc) then sinks after timer or item is grabbed, earthquakes happen on the island when its about to move or goes back underwater.
Could be a Event that Occurs, a Rainbow will indicate where it is or some other Indicator( Example - skull in the sky for Skull forts). What are some of the community Ideas for this????!!