N. Sanity Island is the first of the three islands in a small archipelago of islands near the eastern coast of Australia, sometimes called the Tasmanian Islands. The island is a tropical paradise similar to the other two islands (before Cortex took over the archipelago and completely destroyed the ecosystem of the third island and part of the other islands later on in the series) with lush jungles, beaches and ancient abandoned temple structures.
The island is usually depicted as a small piece of land with a big mountain in the center in which a big skull is carved in one of the sides (sometimes referred to as the Skull Rock). from the Skull Rock a big waterfall comes down, creating a river that separates the jungle from Papu Papu's village, called the Skull Rock Waterfall. The village itself is located in the east part of the island and is protected by two big wooden gates which the natives patrol constantly.
Later games would introduce new elements to the island, such as a series of caves with wooden structures inside, possibly created by the natives to gather resources from the inside of the mountain, first seen in Crash Twinsanity in the level Cavern Catastrophe.
The island can also be seen partially covered in snow during the events of Crash Bandicoot 2: Cortex Strikes Back, a condition that srastically change the look of certain parts of the island.
One of the most famous and recognizable locations on the island is N. Sanity Beach , a sand beach area usually depicted with a big wooden boat shipwrecked on the side and a small narrow path that leads into the mysterious jungles of the island. In Crash Twinsanity this depiction of the beach is dropped in favor of a more open area that extends from Crash's house to the Skull Rock waterfall.
The depiction of the island in Crash Twinsanity is overall quite different from the previous games. The island appears to be smaller in size, with the waterfall located inside the native's territory and far away from N. Sanity Beach, now located right next to the beach. Also the river is not present anymore and the waterfall leads directly into the ocean. Papu's village was relocated to a high up cliff near the ocean, and the natives' territory is much smaller in scope. a river traverses the place but it doesn't seem to be related to the Skull Rock watefall anymore. N. Sanity Beach itself has been changed quite a lot, now lacking distinctive characteristics like the big boat shipwrecked on the rocks and looking more like a generic beach area with tropical trees and grass around it. A small hen-house is located here.
Crash Twinsanity also introduced Farmer Ernest, an emu living on a small farm on N. Sanity Island. Strangely the new character seems to know Crash already even if this was the first (and last) game in which he appeared.
In the Nintendo DS version of Crash of the Titans, the island is taken over by Cortex and his henchmen, probably due to the fact that Crash and Coco no longer lived there at that point in the series, leaving the island defenseless against the doctor. Cortex build a lair on the east part of the island, while N. Gin partially destroyed the west part of the island to build his factory in which he built the parts needed by Cortex to finish his Cortexbot. It is unknown whether the island is still destroyed or not, since usually this game is considered non-canon to the series, and the main version of the game (considered canon) never mentions the island, it is possible that N. Sanity Island was never taken over by Cortex.