Island Dimension is a dimension in which the Smiths (or just Rick and Jerry) live in a small house on a tropical island.
Mooch Jerry and Jerry 5126 visit this reality through hidden entrances through the multiverse, with Mooch Jerry relaxing on water while the local Rick, heavily drunk, asks him where he left his margaritas, confusing him for his Jerry. After Rick leaves, 5126 Jerry and this reality's Jerry emerge from the water, with the local Jerry was confident his Rick did not notice or care if they were present before asking if they want to take a ceviche to go. They later go through this reality while running away from Jacket Jerry and his subordinates.