The Omni-Cave is a cave that holds omni-lava. This place was proven by VoidSansXD when he took a picture of a wall of the Omni-Cave.
There are multiple areas of the Omni-Cave. The first layer is 500 Omni-Meters away from The Omni-Surface and has a bunch of Omni-Light in it. This part is mostly controlled by the Omni-Bears. The second layer has a name, and it's called "The Bat zone" because It's comfortable enough and dark enough for The Omni-Bats to live there. At the last layer, the "Heat zone", is where the Daves live. They live there because it's too bright for them anywhere else, and living in the lava puts a shield around them to protect themselves from the light emitting off of the Omni-Lava.
Outside of it
Outside of the Omni-Cave is The Omni-Surface, which is pretty much just the entrance for the Omni-Cave. The Omni-Bears protect the front entrance of the Omni-Cave by making giant scratch marks on the person who tries to enter.