Byatis

Byatis is a dimenison that is almost entirely water.

Accessing
To get to Byatis, the player must construct a Byatis portal, by placing four chiseled prismite bricks in a cross shape, with one aquanite obsidian in the center. Lightning will strike the obsidian, turning it into a Byatis portal block. Only players can go through the portals, and other entities just go through as if the portal wasn't there.

When someone enters Byatis, they spawn inside a glass sphere. This gives them a small amount of air, and a place to come back to when they go exploring. Usually, the sphere generates floating in the water, though if the portal was built too low (or has an unlucky spawn biome), it can spawn underground.

Traits
Byatis uses the same world generation as the Overworld. However, the sea level is 200 (normally 63), meaning that a significant amount is underwater. In fact, the only terrain that generates above the sea is icebergs in frozen oceans.

Byatis is always day, though when deep down in the ocean, that doesn't really matter. However, even if the time was changed (with commands or otherwise), players cannot sleep (the bed doesn't explode, though).

Environment
Though most of Byatis is dark, the background fog is usually brighter colors.

Advancements
There are only a couple of advancements currently, but more are planned.