Knock Up Stream

Creation
The Knock Up Stream is created by a giant underwater cave filled with gas. At some point of time, the gas pressure is to much and creates a crack in the ceiling, then a giant whirlpool is created from the crack. Once most of the gas got free, the seabed explodes, sending a giant stream upwards.

Appearance
So far, the Knock Up Stream has made 2 appearances
 * When a part of Jaya was shot towards Skypiea.
 * When the Straw Hat Pirates used it to travel to Skypiea.