I didn't notice that drop off. That is a very interesting design! No slope, no "waste!" Did you mark the edge in some way, like you would for a step or bench? Is there any concern someone won't see it, and dive or jump too close to that edge? Has it happened?
The deepest part of my pool is, like, 1' square. My deep end is a bowl, so while I can claim 7.5', it's only in that one tiny spot. I like the idea of a flatter bottom in the deep end, to maximize what real estate is actually deep. No fun to brush a 9.5' deep corner, though, I suppose. My bowl is pretty easy to brush.
the reason for the drop off was exactly that, “no wasted space” in my mind at least lol. There are tile markers all along that drop off coming out of the river and the main pool identifying the drop off. It’s clearly visible due to the plaster color we choose and keeping the water clear of course . The pic I posted was before we balanced the water so it looks a little cloudy. We were only able to use it a couple months and in that time no incidents at all. There is plenty of space for one to just stand in the main pool and hot tub. Brushing doesntake time but with the deck around the spa it’s pretty easy to get the entire bowl brushed along with the lazy river.