- Pokemon LeafGreen Pokemon Mansion: an abandoned research lab on Cinnabar Island hiding the Secret Key
- Access: reach Cinnabar Island using HM03 Surf from Pallet Town or Fuchsia City
- Objective: flip statue switches, drop through floor holes, and recover the Secret Key on B1F
- LeafGreen exclusive: catch Vulpix here, while FireRed players encounter Growlithe instead
- Next step: the key unlocks Blaine's Fire-type Gym, recommended around Lv. 42-48
What Is the Pokemon Mansion in Pokemon LeafGreen?
The Pokemon LeafGreen Pokemon Mansion is a crumbling, abandoned research building on Cinnabar Island, and it is the one roadblock standing between you and Blaine's Fire-type Gym. The Gym doors remain locked until you recover the Secret Key hidden deep inside the mansion, which makes this dungeon a mandatory stop during the seventh stage of your Kanto journey.
The layout is identical whether you play the 2004 Game Boy Advance original or the Nintendo Switch re-release that arrived on February 27, 2026. The mansion also carries some of the richest lore in the game: scattered journals describe a research team's discovery of a Pokemon called Mew and the creation of a powerful clone — the same Mewtwo that awaits you in Cerulean Cave during the postgame.
| Detail | Information |
|---|---|
| Location | Cinnabar Island, southwest of the Kanto mainland |
| Access requirement | HM03 Surf to cross open water to the island |
| Key item inside | Secret Key (found on B1F) |
| Unlocks | Cinnabar Island Gym and the Volcano Badge |
| Trainer types | Burglars and Scientists |
| Notable encounters | Vulpix (LeafGreen), Koffing, Grimer, Rattata |
The journals inside reference Mew and the birth of Mewtwo. If you plan to challenge Mewtwo in Cerulean Cave after becoming Champion, this mansion is where that storyline quietly begins.
How to Reach Cinnabar Island
Before the mansion itself, you need a way across the water. HM03 Surf is the mandatory field move, and you obtain it from the Secret House deep inside the Fuchsia City Safari Zone. While you are in Fuchsia, also return the Gold Teeth to the Safari Zone Warden to receive HM04 Strength, which proves useful in the caves along the way and later in Victory Road.
Two practical routes lead to Cinnabar Island, and both are fully covered in the official Pokemon FireRed and LeafGreen game overview:
| Starting Point | Path | What to Expect |
|---|---|---|
| Pallet Town | Surf south across Route 21 | Shortest option, open water with low-level wild Pokemon |
| Fuchsia City | Surf west through Routes 19 and 20 | Passes Seafoam Islands, stronger swimmers and tentacle encounters |
If you take the Fuchsia route, Seafoam Islands sits directly on your path and houses Articuno at Lv. 50. Navigating the inner caves requires Surf and Strength to redirect the water currents. Save your game before interacting with it, because it is a one-time fixed encounter.
Secret Key Walkthrough: Floor by Floor
The mansion is a multi-floor puzzle built around two mechanics: statue switches that open and close doors, and holes in the floor that drop you to lower levels. Progression rarely runs straight upward — expect to descend through holes and loop back through staircases as you work toward the basement.
Enter and Clear 1F
Walk into the mansion and flip the first statue switch to unlock the doors ahead. Deal with the Burglar trainers near the entrance, then take the stairs upward.
Work Through 2F
On the second floor, flip another statue switch to rearrange the doors. A hole in the floor drops you to a lower level, which is the intended route toward the basement rather than a trap.
Cross 3F
The third floor mixes Scientists and more switch puzzles. Toggle the statues as needed and use the floor holes to keep descending instead of backtracking.
Recover the Secret Key on B1F
Search the basement until you locate the Secret Key. Take a moment to read the research journals here, since they contain the Mew and Mewtwo notes.
Exit and Prepare
Use an Escape Rope or retrace your steps to leave, then heal at the Cinnabar Island Pokemon Center. The Secret Key immediately unlocks Blaine's Gym doors.
| Floor | Main Objective | Hazards and Notes |
|---|---|---|
| 1F | Flip the first statue switch, reach the stairs | Burglar trainers, wild Rattata |
| 2F | Flip another switch, drop through the floor hole | Scientist battles, Koffing encounters |
| 3F | Toggle switches to link paths downward | Grimer encounters, looping layout |
| B1F | Pick up the Secret Key | Research journals with Mew and Mewtwo lore |
Wild Koffing and Grimer inflict poison with alarming frequency, so stock Antidotes or Paralyz Heals before entering. Statue switches also reset door states — if a door slams shut in front of you, backtrack to the last statue you used and flip it again.
Wild Pokemon and Trainers Inside the Mansion
The mansion doubles as one of the better catching spots in the mid-to-late game, especially for LeafGreen players. The encounter table here is where the two versions split most visibly at this stage of the story.
| Pokemon | Type | Version Availability | Why Catch It |
|---|---|---|---|
| Vulpix | Fire | LeafGreen only | Best Fire-type catch here, evolves with a Fire Stone |
| Growlithe | Fire | FireRed only | Requires trading in LeafGreen |
| Koffing | Poison | Both versions | Evolves into Weezing, solid defensive body |
| Grimer | Poison | Both versions | Evolves into Muk, useful physical bulk |
| Rattata / Raticate | Normal | Both versions | Common filler, low value at this stage |
Vulpix: Top Pick
- LeafGreen exclusive encounter
- Evolves into Ninetales with a Fire Stone
- Reliable special attacker for the late game
Koffing and Grimer
- Poison types with strong defenses
- Broad TM compatibility for coverage
- Weezing and Muk hold up in the Pokemon League
Mansion Trainers
- Burglars field Fire-type teams
- Scientists use mixed special attackers
- Solid cash and experience before Blaine
Buy a Fire Stone at the Celadon Department Store evolution counter before or after your visit. Catching Vulpix here and evolving it into Ninetales immediately gives your team a mature Fire-type option without waiting for level-up moves.
After the Mansion: Blaine's Gym and Beyond
With the Secret Key in hand, the Cinnabar Gym opens. Blaine runs a pure Fire-type roster, and in FireRed and LeafGreen his gym uses quiz machines — answering a question correctly lets you skip the trainer beside it, while a wrong answer forces the battle. Answering honestly is fine, but fighting the trainers is worthwhile experience if your team sits below the recommended range.
| Pokemon | Level | Type | Best Counters |
|---|---|---|---|
| Growlithe | 42 | Fire | Water, Ground, Rock |
| Ponyta | 40 | Fire | Water, Ground, Rock |
| Rapidash | 42 | Fire | Water, Ground, Rock |
| Arcanine | 47 | Fire | Strongest threat, keep Surf users healthy |
Surf users perform very well here — Lapras, Blastoise, or Vaporeon can sweep most of the roster. Save healing items for Arcanine at Lv. 47, which hits noticeably harder than everything else Blaine sends out.
The moment you leave the Gym, Bill waits outside and invites you to One Island, starting the first Sevii Islands storyline with the Tri-Pass. Before sailing, consider heading north through Kindle Road to Mt. Ember, where Moltres waits at Lv. 50 as another one-time fixed encounter.
Cinnabar Island Objectives:
- Recover the Secret Key from the mansion basement
- Catch Vulpix before leaving the island
- Defeat Blaine and earn the Volcano Badge
- Accept Bill's invitation to One Island
- Optional: catch Moltres at Mt. Ember on One Island
Pokemon Mansion FAQ
The mansion is fully optional for exploration, but the Secret Key inside is mandatory — without it, the Cinnabar Gym doors stay locked and the story cannot advance to the Sevii Islands.
Q: Do I need a Key Item just to enter the Pokemon Mansion?
No. The mansion is open as soon as you arrive on Cinnabar Island. The Secret Key is the reward you find inside, and it is used on the Gym doors rather than the mansion entrance.
Q: Where exactly is the Secret Key in the mansion?
The Secret Key sits on B1F, the basement level. Flip the statue switches to rearrange doors, use the floor holes to descend, and search the basement thoroughly before leaving.
Q: Can I catch Growlithe in the LeafGreen version of the mansion?
No. Growlithe is a FireRed exclusive encounter. LeafGreen players find Vulpix here instead, so completing both Fire-type families requires trading between versions.
Q: What level should my team be for the mansion and Blaine?
Around Lv. 40-45 handles the Burglars and Scientists inside the mansion comfortably. For Blaine himself, a team in the Lv. 42-48 range with at least one strong Water, Ground, or Rock attacker makes the Gym straightforward.