Bubble Column

A bubble column is a block generated by placing magma blocks or soul sand in water. Bubble columns push or pull entities in certain directions.

Natural generation
When generating the world, caves, ravines and underwater ruins generate below the water surface. When lava generates in the former two, some lava is converted to obsidian, and some to magma blocks, which create bubble columns. All bubble columns generate bubble column blocks until the column reaches the surface of the water or a solid block above the magma block.

Post-generation
When a magma block is placed underwater, a whirlpool bubble column is generated.

When soul sand is placed under source water blocks, an upward bubble column is generated.

Obtaining
Bubble columns cannot be obtained as an item, and can be placed only by a block-placement command such as.

$$, it may be obtained as an item via inventory editing.

Usage
A player or any other air-breathing mob can enter a bubble column to replenish their air supply, at the same speed that they would when they leave the water entirely. Water-breathing mobs avoid bubble columns; they die if trapped in one. A bubble column is destroyed when moved by a piston. When creating a bubble column, all blocks above must be source blocks. This requires either naturally generated water, or for the player to place a water source for each block they would like the column to reach. Bubble columns can also be created in downwards flowing water, however this causes all water to be converted to water source blocks. Bubble columns do not propagate through waterlogged blocks. The height of a bubble column is limited only by the water's surface or by any obstructing blocks underwater.

Whirlpool
Whirlpool bubble columns can be seen by air bubbles wandering downwards. They drag entities downwards. A boat ridden over a whirlpool shakes and eventually sinks if kept above the whirlpool for too long. This has a vertical range of 86 blocks.

Upward
Upward bubble columns can be seen as vertically rising air bubbles. An upward bubble column accelerates entities upwards. The longer an object rises through the bubble column, the faster it travels. At high enough speeds, players and entities can be launched out of water by several blocks. Sitting on the surface above a rising bubble column causes entities to bounce upwards repeatedly by about 1 block.

Transport
Entities move at a speed of approximately 15 blocks (meters) per second when inside a bubble column. This equates to a speed of 900 blocks per minute, albeit only vertically.

Sounds
Java Edition:

Block data
$$, bubble columns uses the following data values:

Gallery
Blasensäule Colonne de bulles 거품 기둥 Kolumna bąbelkowa Столб пузырей 气泡柱