I'm playing Minecraft 1.13 and I know how the new bubble columns work, but I don't know how to make them in compact spaces. I know how to use them in oceans but I want to make one in a 3 x 3 space. I just want to make a bubble column in a 3 x 3 column.
You have two options:
Magma block: it's found in the nether or in ocean ravine, and when placed underwater creates a bubble stream that pulls you down.
Soul sand: it's found in the nether, and when placed underwater creates a lifting bubble stream.
Also, all blocks in your column must be source blocks, or the column will not work.