That tidal bore you saw, Astro tourist must have been quite something. Many years ago, I was in a little 3 metre boat (with 1.5hp Seagull motor) on the River Severn in Gloucestershire. Suddenly behind me I heard a roaring sound, and there coming around a bend in the river was this wall of water.
AAAGGGGHHHH I turned the little boat around and headed straight for the middle where there was still some unbroken water - WOW what a ride! I met it head on, then turned round and followed the tide. Too fast for my anchor, I just ran for the shore, jumped out and pulled the boat up and up, as the tide rose so fast.
The Severn bore is second to that one in China you saw!!