The Depthchutes are a special system of Chutes engineered by the Knights of Mata-Nui.
There is a network of Depthchutes underneat each Metru. They can be controlled from any base of the Knights, however, the flow of them can only be controlled from Tower Top in Ko-Metru. The only way into the Chute System is through one of the three bases of the Knights.
Each base has two Chutes. One goes out, one comes in. Each Chute is paralelled by another going the opposite way. This Chute system is slightly less complex than than the above ground Chute System, however it is significantly faster. In the center of the island, the passanger has the ability to switch to another set of small Chute conduits which links into the central system.