From Bulbapedia, the community-driven Pokémon encyclopedia.
Knot Island (Japanese: むすびじま Bond Island) is the first island in the Sevii Islands archipelago. It is the most northwest of all the islands.
Knot Island is an isolated little place, and most of the younger people living on the island are eager to leave for big cities.
Knot Island is home to the Pokémon Network Center, run by Celio. The Net Center is located in the town of One Island, on the south side of the island. The Pokémon Net Center has a large, long-distance trading machine that enables Trainers to trade Pokémon with others in the Hoenn and Orre regions.
A small area extends to an island south of the town, called Treasure Beach, where valuable items, such as Big Pearls and Stardust, wash up and regenerate.
There is an enormous volcano, Mt. Ember, at the very north tip of the island, and it is reachable via a path known as Kindle Road, which is popular for its hot springs. The hot springs on Kindle Road can restore energy and vitality to Pokémon.
Mt. Ember makes the island a popular tourist spot thanks to the hot springs and climate. Luckily, Mt. Ember has not erupted in years.
Although believed to be inactive, the tunnels beneath the volcano are still warm with geothermic energy that attracts Fire-type Pokémon. Additionally, the presence of a legendary Pokémon on Mt. Ember keeps the peak ablaze with flames at night.
Mt. Ember and Knot Island are home to Moltres in Pokémon FireRed and LeafGreen.
Celio only completes the Net Center after the main character in Pokémon FireRed or LeafGreen brings him both the Sapphire and the Ruby, found on Chrono Island and atop Mt. Ember, respectively.
Locations on Knot Island
In the anime
Knot Island was seen in The Search for the Legend, where Ritchie took a ferry to Knot Island to visit Mt. Ember. Due to a dubbing error, it is referred to as Mt. Magma.
Pokémon seen on and around Knot Island