The Mysterious Abyss (ワンダーオブアビス Wandā obu Abisu?, lit. "Wonder of Abyss") is a Keyblade acquired after defeating Ursula in Kingdom Hearts II and Kingdom Hearts II Final Mix. This Keyblade is the equivalent of the Crabclaw Keyblade from Kingdom Hearts.
The teeth and blade of the Keyblade are in the shape of a water spout. The token is in the shape of a white shell connected to the handle which is made up of assorted shells by a golden chain. In the center of the guard is a shell that has a small blue pearl in the middle.
This Keyblade's name probably refers to the mysterious wonders of the deep sea.
| Kingdom Key | Oathkeeper | Oblivion | Ultima Weapon | Lady Luck | Olympia | Jungle King | Three Wishes | Pumpkinhead | Wishing Star | Crabclaw | Fairy Harp | Divine Rose | Spellbinder | Lionheart | Metal Chocobo | One-Winged Angel | Diamond Dust | Star Seeker | Hidden Dragon | Rumbling Rose | Hero's Crest | Monochrome | Mysterious Abyss | Follow the Wind | Wishing Lamp | Decisive Pumpkin | Circle of Life | Sweet Memories | Photon Debugger | Gull Wing | Guardian Soul | Sleeping Lion | Fenrir | Bond of Flame | Two Become One | Fatal Crest | Winner's Proof | Hero's Origin | Shooting Star | Favorite Deputy | Ever After | Happy Gear | Crystal Snow | Nano Gear | Wheel of Fate | Hunny Spout | Starlight | Grand Chef | Classic Tone | Midnight Blue | Phantom Green | Dawn Till Dusk|
Wooden Sword | Struggle Bat