The Secret Key is found inside of the Pokémon Mansion on Cinnabar Island. The key is lying on a table in a room on B1F in the basement of the Mansion.
You can reach this room by interacting with various statues throughout the mansion, which each unlock walls and passageways leading to the basement.
If you’re looking for the Secret Key to unlock Blaine’s Gym, then you’ve probably already taken care of the prerequisites. But just to cover our bases, here’s what you’ll need:
- Have HM03 Surf and be able to use it
- Be able to reach Cinnabar Island
Basically, you just need to reach Cinnabar Island. The fastest way to get here is to Surf south from Pallet Town.
Once you hit Cinnabar Island, you can get the Secret Key.
Finding the Secret Key
We need the key because the Cinnabar Island Gym is actually locked when we first arrive, so we can’t head inside to challenge Blaine.
The key itself is inside of the Pokémon Mansion on the left side of the Island.
The Pokémon Mansion is the abandoned building with the sign right next to it.
When you’re ready, head inside of the Mansion to get started.
Tip: There will be Wild Pokémon and trainers, so make sure that your Pokémon are healed up.
Entering the Pokémon Mansion
When you first step into the Pokémon Mansion, walk straight north from the entrance.
Walk until you see a staircase & take this staircase up to the second floor.
The First Mewtwo Statue (2nd Floor)
Here you will see the main gimmick of the Pokémon Mansion, a Mewtwo Statue.
The eyes of the statues will either be dim or they’ll be growing red, and you can switch the Statues back and forth.
This will also open and close various barriers throughout the mansion.
So our goal is to flip the correct switches so that we can make it to the end of the Pokémon Mansion.
This first statue should not have red eyes. If it does, then interact with it to flip its switch once, so that its eyes are not glowing.
After you flip the switch, walk out of the room through the right-side exit.
Then make your way to the northwest portion of this floor.
There will be a staircase up here as well, leading to the third floor.
Go ahead and head up that staircase.
The Second Mewtwo Statue (3rd Floor)
There will be another statue as soon as you walk up the stairs. This statue’s eyes will not be glowing, but we want them to.
So walk up to the statue and press A to interact with it, then select Yes when asked if you’d like to press the button.
This will open up the path just southeast of the statue.
Head south and go through the newly opened path.
Once you walk into the new room, you will see that there are two paths that lead to a huge hole in the floor.
We want to walk off of the left path into the dark abyss (trust me on this).
Getting to the Basement
After you fall through the hole, you’ll land right next to a Scientist Ted. Walk south slightly and a staircase will come into view.
Battle Scientist Ted if you haven’t yet, and then take the staircase down to the lower floor.
The Third Mewtwo Statue (Basement Floor)
Once you reach the lower floor, walk slightly left and you will see another statue in the corner of a room (there is a wall in your way).
Make your way into the room and then interact with this statue just like before.
Make sure that this statue’s eyes are not glowing.
After you press the statue’s button and ensure that its eyes aren’t glowing red, make your way back to the staircase we entered through in the southwest corner of this floor.
But do not take these stairs back up.
Instead, from the staircase just head north through the open corridor on the far-right wall.
The Fourth Mewtwo Statue (Basement Floor)
Walk up until you reach the northernmost room.
There is another statue in this room. Interact with this statue and press its button to turn its eyes on (we want this statue’s eyes to be glowing red).
Afterwards, leave the statue room and make your way west down the hall.
The Secret Key on the Table
Walk west as far as you can until you see a table with an item on it.
This item on the table is the Secret Key.
Pick the Poké Ball up to put the Secret Key in the Key Items Pouch of your Bag, and then make your way out of the Pokémon Mansion.
You’ll have to mess with a couple more statues, but leaving the mansion is much easier than entering.
Tip: Bring an Escape Rope to exit the mansion quicker, or consider bringing a Pokémon that knows Dig.
Once you have the Secret Key, you can head directly to the Cinnabar Island Gym and walk through the doors to challenge Blaine!