Tundra Tunnel

Tundra Tunnel is an anomalous level found in some personalized copies of Super Mario 64. It has been described as a cavern-like level similar to Hazy Maze Cave, though made of ice and snowy with several recycled assets from Cool, Cool Mountain and Snowman's Land. This fusion of themes and assets has lead some to believe this level is made through Dynamic Level Arrangement. However, it has also been compared to Cold, Cold Crevasse, potentially being the actual area in question, though this is unlikely.

Description
Tundra Tunnel has been described as a large system of tunnels made up of ice and snow, notably utilizing the unused Cracked Ice texture for some parts of the level, such as parts of the wall that need to be broken to progress. The actual level besides the general description isn't very notable, except for it's odd nature of having several seemingly unrelated enemies appear through Enemy Discoloring, such as Spindels or Goombas, and the unused small Chill Bullies. Regular cave and snow level enemies also appear.

Notably, Tundra Tunnel reportedly has a rare sub-area taking the appearance of an abandoned mineshaft with unique rideable minecarts used to navigate the area. This sub-area supposedly has a unique variant of Monty Mole that would appear in neighboring minecarts and throw objects at the player, such as rocks or Bob-ombs, that would have to be thrown back at the player.

Missions
The most common missions in the level are for collecting 8 red coins in either the main area or the mineshaft sub-area, reaching the end of the sub-area, and defeating a Chill Bully. Some other less common missions are completed by getting past a long series of hallways with multiple Spindels, completing a puzzle by breaking a group of ice blocks in a specific order, mirroring the chest missions found in Jolly Roger Bay and Dire, Dire Docks, and defeating some sort of boss fight in the mineshaft, commonly a more difficult Monty Mole, occasionally even being the Rocky Wrench from Super Mario Bros. 3.