It's a small planet floating in the Ultrverse, A rip in space.
It is completely covered in water, with a solid stone core. It can only sustain life for underwater creatures. Nothing but coral lives on it, but fossils of dragon like things have been discovered by the PSA. The core is stone fused with teace amounts of diamond. The closest thing it has to a sun is a large ball of fire floating under water somehow.
99% of everyone has went there, but not returned.
0.5% returned. and 0.5% died upon returning.