Cold, Cold Crevasse

Cold, Cold Crevasse is an area off-handedly mentioned in Cool, Cool Mountain by a sign near the beginning of the level. The most common interpretation of this name is that it belongs to the slope that preceeds the sign, although it does not match the description of a crevasse.

The recent boom in Super Mario 64 conspiracy theories has brought Cold, Cold Crevasse back as a discussion point, with many theorising it to be an unused or scrapped sub-area for Cool, Cool Mountain.

Existence
There's a sign nearby the broken bridge at the beginning of Cool, Cool Mountain. On it, it reads "Warning! Cold, Cold Crevasse Below!" and below this area is a large slope that leads downwards. It's not much of a crevasse leading some to speculate that this isn't the Cold, Cold Crevasse the sign is referring to. Considering that the name "Cold, Cold Crevasse" follows the common naming conventions for Super Mario 64 stages, it could instead referring to a removed area erroneously still mentioned due to a developer forgetting to change the text on the sign. A crevasse is a deep open crack; this doesn't fit the description well since there is no other side that would make it qualify as a giant crack.

jefftastic's Video
As apart of jefftastic's videos documenting Super Mario 64 phenomena, one of his videos features Cold, Cold Crevasse. He seems to accidentally stumble across a warp to the area while trying to bring the penguin across the slope in Cool, Cool Mountain.

Cold, Cold Crevasse is presented as a secret area within Cool, Cool Mountain featuring only one star. The level has the player trek through the internals of a cavern, where Spindrifts are found to help the player ascend through the tower. The two signs that appear in this level are signed by the kind Chief Snowman. The star collected in this level is considered as one of the secret stars much like The Princess's Secret Slide.

Reportings

 * Everything in this section should be taken with a grain of salt. These are all unverified claims.