Level 12321 resembles a misty river surrounded by trees and grass, but with a yellow tint and a low resolution. The water is shallow and stagnant, and the air is humid and stale. The level is relatively safe, as there are no known entities or dangers. However, it is also very easy to get lost, as the mist obscures the visibility and the river branches off in multiple directions. There are no exits or entrances to other levels, except for random noclipping events that can send you back to Level 0 or to another level.
The only way to escape this level is to find a boat or a raft and follow the river downstream until you reach a waterfall. If you jump off the waterfall, you will noclip to either level 152 or ! but you have a very low chance of noclipping there. However, this is not guaranteed, as some people have reported noclipping to other levels instead. The chances of finding a boat or a raft are very low, as they are rare and often hidden by the mist.
The best strategy for this level is to stay calm and avoid panicking. Try to remember the direction you came from and retrace your steps. If you find a boat or a raft, use it to escape. If not, keep looking for one. Do not wander off the riverbank, as you may encounter unknown dangers or lose your way. Do not drink the water, as it may be contaminated or cause hallucinations. Do not stay in this level for too long, as you may lose your sanity or your sense of reality.