I was very excited to finish up tiling the major area of the back of the waterfall because it really showed the off the tile and the pattern I decided on. I have been waiting for the concrete block to dry out between rainstorms to waterproof the inside of the spa. 
In the meantime, I tiled the top of the waterfall after the one row around the three outside walls.
I decided to tile the back of the waterfall as a good way to get better for tiling the front of the waterfall that will be a little more complicated and more visible. I fit and placed about 100 tiles on the back of the waterfall. All but 15 tiles had to be cut.
I cannot say that I'm very fast at this, so I just take my time to try to get it right. The border around the top arch was a challenge, but with a little patience and a lot of time (mostly getting up and down and back and forth) it turned out pretty well.
The blue tape is to protect areas from the waterproofing application that is next.
