Grelbin was an icy planet, home to enormous ice planes. The deserts were known to be home to precious moonstones. The ice deserts were, however, also filled with ferocious creatures, such as the Arctic Leviathans. The Y.E.T.I.s were genetically engineered to hunt down the Arctic Leviathans; however, they glitched out and overran the planet and became an incredibly hostile race, making the problem worse. There were few facilities located on Grelbin, and the ones that existed were located underground, such as the Mining Facility, which was used to mine for valuable minerals.
When Ratchet landed on Grelbin, he once again encountered the New Age Mystic, who aided him by removing a large ice block which was blocking the entrance to an underground tunnel. The tunnel lead to the Mining Facility, were Ratchet had to battle Receiver Bots v3.0s. After defeating his enemies and flooding the frozen facility, Ratchet was granted access to Angela Cross's Estate. The Estate was almost overrun by vicious Protopets, but Ratchet was able to destroy them. After saving the planet from what would have otherwise become a Protopet infestation, Angela gave Ratchet her ID badge, which allowed him to infiltrate the MegaCorp Headquarters.
Characters on Grelbin
Behind the scenes
Grelbin becomes very, very easy in the high-definition version of Ratchet & Clank: Going Commando, an immense amount of Y.E.T.I. and an attack from an Artic Leviathan at the same time causes Ratchet to become invisible and invincible. It wears off if the player leaves the planet or falls off a pit (or crashing in the Glider path). 
- The water in the facility, as well as the liquid in the bottom seem to have a reflection effect. It is actually a pattern and more specifically the one used as the waves of this water and every ocean in the same and previous games.
- The player can hypnotise the first receiver bot again. Ratchet must fall down and die and, when returning again, use the Hypnomatic quickly before the door shuts.
- The factory is not in reality under the level. Through glitching, one can discover that the factory level is much higher than the ground level; the ship is visible under it.
- It is said that the music in the glider path cannot be played completely. Actually, the whole track can be played if you get back inside the cave and stay. Even interestingly, if the player goes to the spot where the music changes and quickly getting out, it is possible for the music to play for the rest of the level (until the player dies before reaching a checkpoint).