In reply to Grzegorz Dworak.

I think what you are referring to is “Snell’s window”. Here is a link to a wikipedia article on this effect.
https://en.wikipedia.org/wiki/Snell%27s_window
Snell’s window occurs when looking up from underwater and light coming from outside the water is refracted when entering the water. The total internal reflection described in the blog post is concerning light that originates from underwater and is reflected at the water air boundary.