Unused Level 32

Unused Level 32, filename 32NIGHT.bin, is an unused level in Super Mario 64. Unlike all the other unused levels, this is the only level with code assigned to it in the retail game. The code relates to the fish and cap switch objects, both of which have an unused value that checks for which course it is in. If it happens to be the 32nd course, then fishes will despawn if there is no water in its location, and that cap switches will start off unpressed bypassing its current state in the save file. The reason behind these conditions are unknown.

Like many other unused levels, the model for this level was discovered in the iQue leak. The assets attaining to this level prove that, as predicted, Level 32 was intended for testing. Unlike the other unused levels however, this level has multiple variations intended to test multiple objects.

Geography
One variation of the level features some slopes and a steel box that would go on to be used in Wet-Dry World and Bowser in the Sky. It doesn't feature any cap switches or pools of water however.

The other variation of the level causes the game to crash due to it having objects from conflicting object banks.

Theorising
Before the iQue leak, it was commonly assumed that Unused Level 32 belongs to a removed test map due to the strange behaviours associated with the level. The existence of multiple maps can be chocked up to the map being changed to test other objects in game, which is a common occurance in game development.

Interestingly, a test level appears in Super Mario 64 DS and contains switch blocks and cap switches, although they do not carry the same unpressed check as the original.

Unused Level Idea
It's also possible that Unused Level 32 would've been home to an unused course. In the same iQue leak, the level is referred to as "NIGHT", implying that it could be a night-themed level. It could've been the level behind the night sky painting on the Second Floor, which is often referred to as The Starry-Night Skies. It could also be a cap switch course because of the checks for switches. It could belong to the mysterious Yellow Cap Switch.