The Cloud in a Bottle is an accessory that can be found in Gold Chests in the Underground and Cavernlayers. When equipped, it allows the player an extra jump. The extra jump has a 75% jump duration compared to a normal jump, increasing the maximum height the player can reach without other accessories by 5 blocks, for a total of 11 blocks.
The double-jump can be used as a fall safety device; use it shortly before hitting the ground to reset your fall damage and land safely.
Each underwater jump used when swimming with the Flipper will waste a jump provided by double-jump accessories in the order that they would be used outside of water, preventing you from using them once you break the water's surface.