Calvin describes a couple of specific techniques he uses to stop himself from getting stuck in the tightest parts.
For example, in the YouTube video he has a piece of cardboard underneath him which he can use to reduce friction.
Likewise, in another section he described pulling his t-shirt up first, and then moving inside his t-shirt to edge his way forward.
All this with thousands of tons of rock and earth surrounding you.
Call me odd, but that just doesn’t sound fun.

People piled into the comments to share their thoughts about the hobby, and many were horrified at just how small the caves can get.
One person joked: “The best part about caving is you don’t have to do it.”
Another said: “I love waking up every day and having the choice not to do caving.”
A third person found it difficult to even watch the video, saying: “I couldn’t breathe while watching this video.”
Another asked why caving, writing: “Sky diving, deep sea diving, mountain climbing. I can see the appeal and thrill of these activities. WHAT IS THE APPEAL OF CAVING?!”
But not everyone responded like this, with one person commenting it’s good to find something we like doing, but to take proper precautions.
They wrote: “I’m glad you found something you enjoy! Just remember to stay safe!”