One Island FireRed & LeafGreen · Sevii island
One Island is the first stop of the Sevii Islands, which Bill takes you to once you have beaten the Cinnabar Gym. His friend Celio works on a Network Machine in the Pokémon Center here, and the quest to finish it (it needs a Ruby and a Sapphire) runs through the whole Sevii chapter; Bill also hands you a Meteorite to deliver to Two Island. Kindle Road leads north to Mt. Ember and Treasure Beach lies to the south.
- Wild Pokémon
- 12
- Items
- 2
- Trainers
- 0
Connects to: Treasure Beach · Kindle Road
One Island on the Sevii Islands map
Gift and special Pokémon
Entei Lv. 50 · One-off encounterRoams Kanto after you give Celio the Sapphire, if you chose Bulbasaur.
Suicune Lv. 50 · One-off encounterRoams Kanto after you give Celio the Sapphire, if you chose Charmander.
Raikou Lv. 50 · One-off encounterRoams Kanto after you give Celio the Sapphire, if you chose Squirtle.
Wild Pokémon
| Pokémon | Type | Lv. | FireRed | LeafGreen |
|---|---|---|---|---|
 Tentacool | WaterPoison | 5–40 | 95% | 95% |
 Tentacruel | WaterPoison | 35–40 | 5% | 5% |
| Rod | Pokémon | Lv. | FireRed | LeafGreen |
|---|---|---|---|---|
| Old Rod |  Magikarp | 5 | 100% | 100% |
| Good Rod |  Krabby | 5–15 | – | 80% |
 Horsea | 5–15 | 80% | – | |
| Magikarp | 5–15 | 20% | 20% | |
| Super Rod |  Shellder | 15–25 | 40% | – |
| Krabby | 15–25 | – | 40% | |
| Horsea | 15–25 | 40% | – | |
 Staryu | 15–25 | – | 40% | |
 Gyarados | 15–25 | 15% | 15% | |
 Kingler | 25–35 | – | 4% | |
 Seadra | 25–35 | 4% | – | |
 Psyduck | 25–35 | 1% | – | |
 Slowpoke | 25–35 | – | 1% |
Chances are the game’s encounter slots for each version (grass 20/20/10/10/10/10/5/5/4/4/1/1, surfing and Rock Smash 60/30/5/4/1, Old Rod 70/30, Good Rod 60/20/20, Super Rod 40/40/15/4/1). A dash means the Pokémon does not appear in that version here. Version exclusives · Where to find every Pokémon.
Items
| Item | How |
|---|---|
| Tri-Pass | Gift |
| Town Map | Gift |
Hidden items sparkle with the Itemfinder.
Tips
- Talk to Celio in the Pokémon Center to receive the Tri-Pass (it lets you take the Seagallop between Vermilion City and the first three islands) and a Town Map or an extra Town Map page.
- The Network Machine is finished only after you return with the Ruby from Mt. Ember and the Sapphire from the Five Island Rocket Warehouse, which comes later in the post-game.
- There are no wild Pokémon on land, but Surfing here has Tentacool and fishing differs by version: Horsea and Shellder in FireRed, Krabby and Staryu in LeafGreen.
- Use the Pokémon Center here for healing before walking Kindle Road, since the trainers on it are around level 35 to 39.
Walkthrough: Part 12: One to Three Island with Bill and Celio · Part 15: Sevii Islands Four to Seven
FAQ
How do I get to One Island?
Bill invites you at Cinnabar Island after the Cinnabar Gym and takes you there; afterwards you use the Seagallop with your Tri-Pass.
Where do I get the Tri-Pass in FireRed and LeafGreen?
From Celio in the One Island Pokémon Center, when Bill asks you to carry his Meteorite to Two Island.
What does the Network Machine do?
Once Celio has the Ruby and the Sapphire it links your game with Hoenn, and it also unlocks Cerulean Cave.
What Pokémon can you catch in One Island in FireRed and LeafGreen?
12 species: Tentacool, Tentacruel, Magikarp, Krabby, Horsea, Shellder, Staryu, Gyarados, Kingler, Seadra, Psyduck, Slowpoke. FireRed only: Horsea, Shellder, Seadra, Psyduck. LeafGreen only: Krabby, Staryu, Kingler, Slowpoke.
Sources & picture credits
Guide text is original retrogameindex writing, checked against Bulbapedia and the game data. Wild Pokémon and encounter chances for both versions, items, trainers, gifts, trades and shops come from the pret/pokefirered decompilation (pret/pokefirered 037335f4c7). Maps and sprites © Nintendo / Creatures / GAME FREAK, archived from the Bulbagarden Archives; the region maps are drawn from the game’s own map graphics (listed on the image gallery).