How to build a house on the bottom of the sea and pump water in my world

To build a house and pump water under the sea in My World, you can do the following:

Build an area large enough to contain the sea water, which can be done by building walls using cubes such as rocks and dirt.

Use squares or objects to enclose the seawater that needs to be kept from being pumped.

Use the /fill command or the /setblock command to fill air cubes to create a large "bubble" of air above the enclosed sea water.

Use the /fill command or the /setblock command to replace all the water cubes in the enclosure with air cubes, which will pump all the seawater out of the enclosure.

If you need to refill the area with seawater, use the /fill command or the /setblock command to replace the air cubes with water cubes.

It should be noted that building a house on the bottom of the ocean requires a certain amount of skill and experience, and requires players to keep trying and figuring things out. Also, building a house in the game requires consideration of the game's version and rules to avoid unforeseen problems. It is recommended to pay attention to the accuracy of the coordinates when using the /fill command or /setblock command to avoid affecting other areas in the game.