The Eterna Forest (Japanese: ハクタイの森Hakutai Forest) is a forest located in western Sinnoh. It lies on Route 205, separating the two portions of the route, which leads to Floaroma Town in the south and Eterna City in the east. The forest is also the location of the Old Chateau, which can be found in the very northeast.
The Eterna Forest is enveloped in chilly air. Thick stands of trees turn the forest into a natural maze. The forest is home to many Bug- and Grass-type Pokémon, and it is one of only two places in Sinnoh where wildMurkrowDBD/MisdreavusPSP can be found, the other being the Lost Tower.
The Eterna Forest has a reputation for being a mysterious place, from the abandoned Old Chateau to the strange Moss Rock. Known for its long and complex structure with winding, tree-shaded paths, the Eterna Forest is a large natural maze, leading many travelers astray. It has apparently been, for unknown reasons, the location of numerous Team Galactic sightings. The Eterna Forest is home to many Bug- and Grass-type Pokémon, and is the only known place in the Sinnoh region to find and catch Buneary. The forest can be broken into three sections: the southwestern corner, the southeastern corner, and the northeastern corner.
There are several paths that can be taken to get to each entrance; however, the most direct route from the southern part of forest to the forest’s northern exit can be taken by traveling east from the entry, through the tall grass, then directly north to a small gap in the tree that travels east to the northeastern segment. If, however, the western road is taken, the route would lead to an Antidote, and the Moss Rock further north.
The next section of the forest is larger than the first, as by traveling south, through the large patch of tall grass, the road lead to four sections of trees that are placed in a two by two pattern that allows the path to travel through the tree, in a similar "+" shape. There are several items scattered around the area, as well a few Trainers that are eager for a battle. By traveling northeast, the road will soon lead to a large gap, where the road travels north to the northeastern segment.
The third segment turns east where a large square with a dense layer of trees hangs in the middle. Simply traveling north through another patch of tall grass will clear the section. To the north is the Old Chateau where Cut is needed to clear the trees, and to the east is the eastern entry to the forest. This access point leads to eastern Route 205, and Eterna City after that.
The Moss Rock in Brilliant Diamond and Shining Pearl
A mossy rock is located on the far west side of the forest. It emits a kind of radiation, which extends to cover the entire forest. This causes Eevee to evolve into Leafeon when leveled up within the forest's boundaries except for the Old Chateau. The rock itself is located in the southwestern section of the forest near a formation of trees that resembles a sideways L. Directly to the trees' left is Moss Rock, surrounded by long grass.
Lucas and Gardenia outside the Old Chateau in Platinum
The Old Chateau is located in the north of the Eterna Forest, near the eastern entrance. To gain access to it, the player needs Cut, which can only be used after defeating Gardenia in Eterna City.
There is a television inside one of its four bedrooms, which, if interacted with at night (only after obtaining the National Pokédex in Pokémon Diamond, Pearl, Brilliant Diamond, and Shining Pearl), initiates a battle with Rotom.
The Insect Plate can be found hidden on one of the exterior walls of the Old Chateau.
Once the player can use Cut as a field move, they can take a shortcut around the forest, providing quick access between the northern and southern portions of Route 205. On the path there is a woman who will give the player a Big TreeDPPt/StickersBDSP. There is also a Honey Tree and a plot of soil suitable for growing Berries.
When the player first enters the forest, Cheryl will be waiting by the entrance. She is one of the Stat Trainers, specializing in the HP stat. She asks the player to accompany her through the forest, fearing an encounter with Team Galactic.
If the player leaves the forest via the south entrance, Cheryl separates from the player and waits for their return. When the player and Cheryl reach the northeast exit, she leaves and thanks the player. In Pokémon Platinum only, she gives the player a Soothe Bell as a parting gift.
While Cheryl is with the player, all wild battles become Double Battles, and all Trainer battles that would otherwise be Double Battles become Multi Battles. After every battle, she will completely heal the player's party.
In The Grass-Type Is Always Greener!, Ash and the group help Cheryl search for the Amber Castle deep in the Eterna Forest, and meet Gardenia, who challenges Ash to a battle. Gardenia wins, and decides to help the group search for a spot where she knows where Combee gather to form a Combee Wall.
In An Angry Combeenation!, the group spot their first Combee Walls, and eventually make their way to the Amber Castle with Mothim's keen sense of smell. After defeating Team Rocket who were attempting to steal the Enchanted Honey, Cheryl receives a gift of Enchanted Honey for helping Vespiquen and the Combee.
The Eterna Forest appeared in Robust Rotom, where Diamond, Pearl, and Platinum traveled through it on their way to Mt. Coronet. Pearl wondered if there are multiple paths through the forest, only to learn that there are no paths shown on Platinum's Town Map. After reading a tourism guide book, the trio learned that it takes more than a day to pass through the forest, and that there are no lodgings to rest at. Pearl, fearing that Platinum would cry if she has to sleep outside, ran off, with Diamond chasing after him, only to discover a large manor that was not mentioned in the guidebook. Platinum then arrived on her Ponyta and declared they'd stay at the manor for the night, assuming that Diamond and Pearl were trying to fool her when they said there was no place for them to sleep at.