Varrock Ruined Sewers

Varrock Ruined Sewers is an area of Runescape that is unlocked during Underworld and Attack of the Rebels

History
25 years before the events of the game a group of wizards had a duel but one cast a powerful spell which caused lots of flooding. The Ruined Area of the sewers is where the water seeped in. As the fish from the river Lumb got stuck. Plus chemicals leaked and a nightmare potion also fell in. Overnight there was an earthduake which caused several mutations. This is how the Acia-Fish and there god was created.

A year before the game A group of rebel humans came and inhibbited the sewers and formed a gang. The Sewers are where they operated.