How to Get There
When right-clicked once, the Nightmare Bed will ominously warn players about the danger of Vethea. If right-clicked again, the player will be taken into Layer 1 of Vethea. Note that the Nightmare Bed is only usable at night.
Be aware that you may not take any items from the Overworld into Vethea (or take anything from Vethea into the Overworld). Instead, when you enter Vethea, your inventory is cleared, and you will get those items back when you return to the Overworld. The same goes for when you leave Vethea for the Overworld.
Here is a list of mobs in Vethea:
On March 3rd, screenshots of Vethea were released.