It's get very dark in the ocean. This makes it very hard to use anything in the Mariculture Mod.

Could we have a option to change how dark it is under the sea?

Do Water Breathing Potions & Night Vision potions not work properly? Or do you just not want to use them?

Night Vision potions work fine. Water Breathing Potions don't help you see.
The Respiration enchant doesn't help.

In particular Mariculture adds diving equipment to help you see under water. However with Hardcore darkness all it does is let you see the darkness clearly.

Water Breathing removes the underwater fog. With both active i can see perfectly fine underwater.

I'll look into Mariculture

Anything new on this? Night vision makes the goggles pointless, as it makes everything bright as day.
It only takes a few blocks of water to completely black out the floor of the ocean with Hardcore Darkness