You may have seen my Phoenix challenge, and this is basically the thing to oppose this. Enjoy!
You may not go in fire.
You must spend 10 minutes every 20 minutes in water
You must build your home underwater
You may not hold, flint n steel, lava bucket, any fire aspect / flame tools
You get a 8 minute water breathing potion every 8 minutes.
You get a nightvision potion every 8 minutes ^
Get a strength potion everytime your in the water.
If you want to kill a guardian or squid, you may o into creative mode, kill them and delete whatever you spawned in, and back into survival.
Conquer a sea temple and make it your home.
Create a temple for yourself in a village with a blue/green/cyan colored beacon.
Find another village and conquer it by killing all the iron golems and trading with 10 of the villagers, posting a phoenix banner everywhere and building walls around, including a temple. Do this to 3 or more villages.
Get pets of every water mob, nametaged.
After you kill 2 withers, and finish ALL the goals, you can FLY and spawn a end portal, and kill the enderdragon, if you finish this, YOU WON