How do I make a new Minecraft world full of water?

I want to create a new world in Minecraft,
Creative mode, where instead of grass is just water.
So a level only with water and all over the world.

https://minecraft.tools/en/custom.php

Create custom world, enter preset.

There's the choice World Options - Worldtype Standard you have to click 4 times. There's then Worldtype Buffet and Customize. Click customize and choose what you are looking for.

LG cucumber501

Hope I could help!