[jonhendry18]

I would guess the "sub" was not much wider than the kids. While an adult or kid couldn't get through while wearing a cylinder, a cylinder a little bigger than a kid (or smaller than the torso of a Navy SEAL) might get through.

The problem may have been more that it would be too long to navigate some bends in the caves.

It also occurs to me that, being made of aluminum, the tube would act like a giant heatsink in the cold water, chilling whoever was inside.

But with more time before the rescue, and by consulting with divers familiar with the caves, the problems might have been worked out.

So, yeah, taking the tube to Thailand was kind of pointless, but I guess at least shows that it wasn't just empty tweeting. There was an effort.