Pluto Grave

Pluto Grave (冥王星の墓 Meiōsei no Haka lit. Pluto's Tomb), more commonly known by the outside world as Pluto Grove, is a massive forest that has appeared on the Spring Island of Marcella.

Originally your average forest, it grew dangerously out of control due to Affra Amethyst and her Devil Fruit's applications, causing the forest to grow so large out of control that it engulfed a massive portion of the island. This in-evidently caught the attention of many, with the former hunting grounds of Marcella's people being swallowed by Pluto Grave, with all whom enter never being seen again.

Trivia

 * This forest acquired it's name, Pluto Grove, due to being a place where various individuals vanished without a trace. Believing it to be a curse from the god of the underworld.
 * This however mirrors Amethyst reason for calling it Pluto Grave, equating her "curse" as something that delivers all those around her to their death, naming the forest Pluto Grave in hopes her curse would finally die here.