Tanetane Island (タネヒネリ島 Tanehineri Shima, literally Tanehineri Island) is a location in Mother 3. It is home to the Magypsy Mixolydia and her octopus friend, Ocho, as well as enemies such as Unwelcome Gusts, Titanians and the powerful Barrier Trio, who guards the fifth Needle. It is also infested with a type of chimera called Monkalrus.
When the party is first washed onto the island, they are weakened, having only 1 HP and no PP. They decide they must look for food, and soon after they come across some Hallucination Mushrooms. Everyone in the party, with the exception of Boney, eat the mushrooms and start hallucinating. The mushrooms cause everyone except Boney to think that enemies on the field are people that they know, such as Flint, Claus, and the employees of Club Titiboo, including Kumatora's alter ego, Violet.
Many of the hallucinations in Tanetane Island are intended to be menacing. For example, a hallucination of Claus says "Everyone's waiting for you. Everyone's waiting to throw rocks at you, spit in your eyes, and make your life hell. Who's everyone? Everyone you love." and Flint says "I'm gonna beat you. Daddy's gonna beat you, boy."
One of the first enemies which can be encountered is the Zombieshroom, which they believe to be Flint. When the party enters combat with any enemy on the island, all they see is an Eerie Smile, much like the Squatter Demon of EarthBound. Whenever the party approaches, or is near an enemy, Boney will start growling signifying that they are near a foe. The party even sees the Item Guy, who runs his traveling caravan, as an old man with a caravan.
When the party reaches Mixolydia's home, they see the Mole Cricket shop as a lotus root. They also see Ocho as a male sailor instead of an octopus. They see Mixolydia as a regular woman, until she hits them each, including Boney, on the back of the head with a 2x4 in order to knock them back to their senses. After that, she opens the gate leading to the fifth Needle. The party ventures through the area behind the gate, all the while fighting nothing but Unwelcome Gusts, until they finally reach the Needle, and its guardians, the Barrier Trio.
After a long, drawn-out fight with the trio, Lucas finally has an opportunity to pull the Needle. Unfortunately, before he can, the Pigmask Army comes in, and the Masked Man zaps Lucas and his friends with a lightning bolt. Before the party can recover from being zapped, the Masked Man pulls the needle and flies off with the rest of the army. Mixolydia then comes to the party, and gives Lucas her memento and a Jar of Yummy Pickles for Ionia, the next Magypsy they will meet. She then disappears, and the party makes their way back to her house, where Ocho decides to give them a ride back to Tazmily Village. They go to the shore of Tazmily beach, where they started their sea floor dungeon walk.
- If one tries to hack and try to increase HP or PP, it doesn't result in HP or PP being changed. Also, giving a party member a restoration item will result in it being in the inventory, but when used it will not restore HP or PP.
- The EarthBound equivalents of Tanetane Island is said to be Deep Darkness and Moonside. This is because of the former's marshy areas and that it is also only accessible by water, whereas the latter is also based on hallucinations and colored differently from what it should be.
- The word Tane means seed in Japanese. This might be refering to the island's abundance of fauna.
- On Tanetane Island, during Lucas and friends's hallucinations, there is what appears to be a beautifully decorated hot spring that Boney refuses to enter with a mirror beside it. After the hallucination, returning there reveals what once appeared as a hot spring is actually a pool of sludge and that the mirror is a door to the real hot spring. The pool of sludge can still be entered, without being healed and without Boney in the pool.