Do you ever wish for a potion effect where you can breath in water but drown outside of water like a fish? Now you can have that with this simple mod that adds one potion effect. Water Bound. Water Bound potion effect gives you the ability to breath underwater but when you are out of water you can only stay out for 16 seconds until you take damage. There is also an undead potion where you take damage from the sun and a water adversity potion which causes you to take damage when you are in water or rain. A potion effect called Flame that requires you to be burning or in lava (burn damage won't be taken) or else you will start taking damage has been added.
I will port to 1.18 as soon as a snapshot m creator version for 1.18 comes out
Click Images for recipes and "source code"