Animal Island

Animal Island, also known simply as the island, is a resort that appears in and. It is a small island inhabited by a sole inhabitant known as an islander, and also contains an empty bungalow which can be freely used by the player. Upon the first visit, the player will be asked by Kapp'n to name the island. The island will generate in one of a few different layouts, and it contains its own flag post, allowing for some degree of customization. In, the island is shared by all players in town. In, each player can acquire their own personal island. The island can be named, and "Island" will be appended to the chosen name.

In both games, the island can be reached by riding across the sea on Kapp'n's boat. The island is implied to be located far to the south of the town, as the climate is always summer. Upon returning to the mainland, the island can be sent to a Game Boy Advance where the player may continue to interact with their islander, or trade islands with another town's player.

Traveling
The island can be reached by talking to Kapp'n at the town's dock, who will offer a boat ride to the island as he sings a sea shanty. Upon the very first visit, Kapp'n will ask the player for the name of the island they wish to travel to. This name will become the island's permanent name, which cannot be changed. Additionally, the game will append "Island" to the end of the player's chosen name e.g. "Animal" becomes "Animal Island."

In Animal Crossing, a Game Boy Advance must be connected via a Nintendo GameCube Game Boy Advance Cable in order for Kapp'n to appear, but the system can be turned off once Kapp'n begins his sea shanty. In, Kapp'n will always appear, but each player can only travel to their own island once they repay their entire mortgage to Tom Nook; the player can name the island upon purchasing it.

Whale
When traveling to Animal Island, there is approximately a 1% chance of a large fish shadow — about 20 times the length of a sea bass shadow — appearing in the sea, commonly inferred by the community as a whale. The fish cannot be caught under normal circumstances. However, if spawned in a body of water in town via memory editing, it can be caught, and the resulting fish is an arapaima. The fish, for the most part, functions identically to a normal arapaima, though its catch quote is replaced with Mabel's dialogue used when entering Able Sisters; attempting to catch it with full pockets softlocks the game. It is most likely a whale, as its data internally is referred to as "whale_data." It should also be noted that it can still spawn even if the player uses glitches to walk into the open ocean, so getting it to spawn isn't tied to Kapp'n's boat ride.

Climate and geography
Upon the creation, the Island's layout will be randomly chosen between different formations in two different acres; acres can be small islets connected by a small wooden bridge, or a single landmass of various shapes. The island contains two bungalows, one belonging to the islander, and the larger bungalow serving as a shared house for all the town's players. As there is no Gyroid outside the bungalow, it is not possible to save on the island. A flagpole is located near the dock, and the flag can be customized with a design by interacting with it. The island's exterior contains multiple flowers and coconut trees, and shells will commonly appear along the beach.

The weather is always summer on the island, regardless of what season the town is experiencing, and therefore summer-season fish and insects are always available. In, this is the only place that the puffer fish, blue marlin, birdwing butterfly and hercules beetle can be caught. The island also experiences clear weather or rainfall independently of the weather in the town. The player can tan when outside in the sunny weather.

Islanders
Each island has a single villager. In, it can be one of 18 villagers unique to the island and they will be randomly chosen upon the village creation. In, an additional 18 new islanders are included, making a total of 36 available. Unlike the previous games, the island is initially uninhabited and an islander's e-card must be scanned using the e-Reader. This will cause the islander to wash up on the island's beach in a similar fashion to Gulliver. Once rescued by the player, they will move into the smaller bungalow.

The islander will often request specific furniture items from the mainland. Once a requested piece of furniture is brought to the islander, they will offer to buy it to use for decorating their bungalow. Islanders can also ask for various items in the player's inventory, such as unrequested furniture they will also decorate with or clothes they will change into. Islanders will regularly rearrange their home layouts and return furniture items they were not able to use.

Exclusive items
Several pieces of furniture and clothing can only be acquired from the island. In these are obtained via the Game Boy Advance (see below), while in  they can be obtained as gifts from islanders due to the island no longer being connected to the GBA. There is a 5% chance to receive the NES games, and a 95% chance for other items. This is the only way to obtain the Wario's Woods and Baseball games.

Game Boy Advance
In, the island is only accessible by connecting to a Game Boy Advance. The player can leave the island and return to the mainland by speaking to Kapp'n, who will ask if the island should be saved to the Game Boy Advance. Once the island is loaded onto the Game Boy Advance, the player can interact with the villager on the island, helping them catch fish, eat fruits or coconuts left on the ground, dig up buried items, chop down trees, or catch flying presents. The island-exclusive items are only obtainable through this feature.

Any changes made to the island on the Game Boy Advance can be uploaded to the Nintendo GameCube the next time the island is visited; other town's islands can also be visited or more permanently traded.

In, the island minigame is no longer present, and the GBA is not necessary to visit the island; however, it is necessary to scan an e-Reader card in order to have an islander.

Trivia

 * The track "K.K. Island" can be obtained as an aircheck in and . It features a rearranged version of Animal Island's music, omitting the  leitmotif, and is only available by request. In, it is one of three tracks that may play after entering an invalid song request.
 * Through a memory editor, one can see that Animal Island is pre-generated alongside the town, including the islander as well.
 * On some islands, there is a chance that the flagpole on the island will be its own separate island with a small bridge connecting the two islands together.