How do I cover my entire world in water?

Solution 1:

You can brute force this with the clone and fill commands, along with a few command blocks.

⚡️ Get Command Blocks

You can't craft command blocks, nor can you find them in the creative menu. Instead you'll need to use the give command to give yourself one:

give @s command_block

💡 The Concept

In order for this to work, you need to create a self replicating system. It's slow, but, it'll work. This answer will create a basic system that uses a stack of command blocks to wrap itself with stacks of command blocks. So we'll start with a single column, and the world will slowly fill with more and more columns by creating 3x3 grids:

In the screenshot above, the emerald block represents the initial column, and the gold blocks represent the columns it creates. Since each of the newly created columns are exact copies of the original column, this creates a recursive system that self replicates forever.

For the purposes of this post, I will NOT be demonstrating how to stop the system, but it can be stopped with the scoreboard and testfor commands and some changes to the layout, taking into account the rules surrounding water.

⌨️ Placement and Commands

For this to work, you'll need to create a 10 block high column of command blocks that feed into each other. I highly recommend building this in the sky as I did so that structures are unimpacted, but you can place it anywhere. The commands are as follows, assuming that the lowest command block is line 1 and the highest is line 10, respectively:

clone ~ ~ ~ ~ ~10 ~ ~1 ~ ~
clone ~ ~-1 ~ ~ ~9 ~ ~-1 ~-1 ~
clone ~ ~-2 ~ ~ ~8 ~ ~ ~-2 ~1
clone ~ ~-3 ~ ~ ~7 ~ ~ ~-3 ~-1
clone ~ ~-4 ~ ~ ~6 ~ ~1 ~-4 ~1
clone ~ ~-5 ~ ~ ~5 ~ ~-1 ~-5 ~1
clone ~ ~-6 ~ ~ ~4 ~ ~1 ~-6 ~-1
clone ~ ~-7 ~ ~ ~3 ~ ~-1 ~-7 ~-1
fill ~ ~-125 ~ ~ ~ ~ water 0 replace air
fill ~ ~-10 ~ ~ ~ ~ water

The way this works, is that each clone block is responsible for cloning the entire column to one of the surrounding coordinates. Then, the last two blocks are responsible for replacing air with water and removing the command blocks.

📝 Configurations

The configurations are relatively straightforward. The lowest command block (block 1) is the only one with a repeating configuration:

Repeat
Unconditional
Always Active
100 Tick Delay

🚨 Note: Do NOT set the configuration for the lowest command block until all others have been set. If you trigger the system before you're done with all the other command blocks, they will begin overwriting each other, preventing you from finishing the system and forcing you to create a new world.

Command blocks 2 through 8, plus command block 10, should be given a chain configuration with the no delay:

Chain
Conditional
Always Active
0 Tick Delay

Finally, the 9^th command block should be given a delay of less than or equal to the delay in ticks used for the lowest block, to ensure the newly created columns don't overwrite it:

Chain
Conditional
Always Active
50 Tick Delay

🥳 The Result

A world full of water!

🎲 Be Careful

Since this is a recursive system, it may take a few attempts to get it right, so work with it in a new world until you understand what it's doing, and are confident that you won't botch the setup: