Maelstrom

The Maelstrom is unarguably the acid trip of the cosmos. This is one one of the two planes that are unarguably infinite, the other being the Abyss. The Maelstrom contains literally every time, terrain and creature. The place constantly shifts and turns. A blue-red jungle may boil away to reveal the most beautiful glowing lake filled with fish that sing classic blues.
The constant generation of random terrain and creatures makes the Maelstrom an unimaginably dangerous place for the living. In addition to more mundane things like vampiric mosquitoes and volcanoes the size of planets the Maelstrom contains it's own native races of shapechangers, who are capable of shifting along with the chaotic terrain, nullifying some of the danger for themselves. For those who ended up here in their afterlife, this is a place of pure and total freedom. If you're in tune with the plane and able to roll with it's punches it presents and endlessly fascinating, endlessly exhilarating experience.
The Maelstrom has no fixed time or geography, and as such is a haven for powerful arcanists who're on the run. if you're able to find a relatively stable spot and lock it down, you can build a fort that you're infinitely guaranteed that no one will ever find.
Why would you want to go there?
Because you're completely mad. You will never get a cup of tea again. You'll spend your morning fighting a dinosaur then spend your lunch running away from a volcano of white-hot diamonds then you'll skip dinner because the goat you just killed and roasted tastes like rhubarb icecream. Wait a moment, that's totally awesome.
"Lost among all the excitement is one of the oldest questions of planes and philosophy. "If the Maelstrom and Abyss are essentially infinite, if I travel to a random point in the multiverse, would I be more likely to find myself in the Abyss or Maelstrom?"
Put another way, many scholars assume that one plane or the other is "less infinite" or even technically more finite than the other. This is a very important question, especially for one studying planar boundaries and the effects located along these boundaries.
The Author strongly holds the opinion that it is the Maelstrom that is infinite, and that the Abyss is just a particularly nasty subsection of it."''
-The Archmage Speigal