Air under water in space (Minecraft)?

We want to build something underwater right now, but we can't get the water away. How do you do that?

You can use a sponge, but be careful not to let the water come out.

How do you build a sponge?

How swam What makes such a sponge?

I thought these things were pointless xD

Does it pull all the water out of the room or from a circle?

I always filled everything up with blocks and then dismantled them

You can get a sponge in water temples. You have to replace all water blocks with normal blocks and then dismantle them.

Sponge clears water away in a think three blocks radius

Build a room under water (the room is full of water)
Place a sponge in an enclosed space.
Dismantle the sponge and bake it in the oven so you can use it again to remove all of the water.
Finished.

You can find sponges in underwater fortresses… You can't craft them.

If you don't have a sponge, you have no choice but to build the space as a solid block and then hollow it out.

I just googled a bit, really cool, I didn't know. But it's stupid that in Survival it doesn't seem so easy to get there. World edit can also be used in creative

Okay top to bottom or does it matter?

Does a sponge suck a lot of water? Or just a block of water.

You have to replace all water blocks at the same time so that the water does not come new.

Within a certain radius around you, no problem, 5 blocks or so…