This means defeating Clayton and the Stealth Sneak heartless. Once that’s done you’ll be thrown up onto a ledge with an entrance to a cave – enter the cave and climb all the way to the top, slowly making your way up & over to the left. All way the in the top-left of this cave you’ll find a secret room with the keyhole. Just enter this room and a cutscene will automatically start with Sora sealing the keyhole for the world, which leads to one final cutscene back at the Campsite. You’ll unlock the Red Trinity after all these cutscenes (plus you’ll get a few other nifty things too). You can use this new ability (Trinity Charge) in a variety of places, but the most important spots are in Traverse Town where you’ll need to activate Red Trinities to progress the main story.
Where Are All The Red Trinity Spots?
There are a 6 total Red Trinity spots throughout KH1 & KH1.5 where Sora, Donald, and Goofy can use Trinity Charge. Here’s a full list with screenshots:
Traverse Town Item Shop (First District)
Find this at the end of the short alleyway behind the Item Shop. Activating it will open access to the Alleyway area that was originally blocked off by lots of crates stacked-up. But entering with Red Trinity leads you to a chest with Dalmatian Puppies inside.
Traverse Town Waterway (Alleyway)
Get here by going into the Second District Hotel and leaving out any of the balconies, or through the side door next to the Water fountain. Then go all the way to the back wall (towards the Dalmatian’s House) and you should see a small waterway with a drainage grate at the end of the alley. This has a Red Trinity that will give you access to the Secret Waterway area.
Traverse Town Gizmo Shop Roof (Second District)
On the Gizmo Shop’s roof at the very top, you’ll see a wooden wall blocking something behind it. Use Red Trinity on this spot along the back wall to gain access to the bell, which you can ring 3 times to reveal Traverse Town’s Keyhole.
Agrabah (Cave of Wonders)
Disembark in the Treasure room and look for a Red Trinity located in front of the statue. This will reward you with a Mythril Shard and 333 Munny.
Halloween Town (Oogie’s Manor)
In the original Kingdom Hearts for PS2, the spot for this trinity is in the first room after crossing the bridge. But in the original game this spot cannot be accessed after you’ve defeated the Manor’s. So if you’re playing on PS2 you’ll need to remember to activate this before the final boss fight, or you’ll be out of luck & it’ll never be accessible. If you’re playing KH1.5/Final Mix, this trinity spot will instead be on the arch below the Manor. Either way, you’ll be rewarded with a Mythril Shard.
Hollow Bastion (Entrance Hall)
Disembark in the Library and then go down the stairs and find your way back to the Entrance Hall. Then make your way up to the second floor and look for a Red Trinity in front of the tusked stone statue. Activating this spot will give you an Emblem Piece, which is necessary as part of the story progression.
