Pocket realm

A Pocket Realm is a small realm created by a god that exists within the space of another realm. Because only Gods can create them, and are often the only ones capable of accessing them, very few Pocket Realms are known to the world. During the Third Age, when Guthix implemented the edicts, some Gods hid in Pocket Realms in order to trick Guthix into thinking they had left Gielinor, the most notable examples being Zamorak and Armadyl.

Zamorak's Pocket Realm
Zamorak wasted no time in creating his own Pocket Realm after attaining Godhood, using it as a space to relax and prepare for battle in secrecy. When Guthix implemented the Edicts he fled to it, and remained there for the entire fourth age, giving Guthix enough time to fall back into his slumber.

In year 168 of the 5th Age Zamorak used his pocket realm as a "Home Base" in his fight against the Zarosian Musicians, and for the first time he allowed mortals inside of it: Spiffy and Glowie, who initially mistook it for a form of hell.

In 169 Zamorak used the realm again as a means of eluding Zaros and his forces, though Zaros was able to use his Godly powers to allow Char access to pursue him. The Trio intercepted and killed her before she could reach Zamorak, and together the four used the realm as a staging area for their final assult on Zaros and his allies.

Armadyl's Pocket Realm
Unlike Zamorak, Armadyl did not create his Pocket Realm until the Edicts were implemented. Not wishing to abandon Gileinor, and not trusting the other gods to obey Guthix's demands, he quickly created an empty realm which he could use to hide from Guthix. As time passed, though, Armadyl came to value the realm as a place for meditation and a place where he could store powerful, or dangerous, artifacts, such as the Staff of Armadyl. Eventually he would imprison Guthix himself here, who would later destroy the realm when he escaped.

Armadyl's realm is completely inaccessible by anyone other than Armadyl and those he chooses to let enter, whereas Zamorak's realm has locked surface access on Gielinor. This makes it far more secure, and practically impossible for other Gods to find. The only other people to have ever stepped foot into Armadyl's realm are Zamorak and Guthix, though the latter was not by choice.