It all depends on how you dig the hole. If you had a completely flat bottom, I think the water depth is about 38" because the skimmer mounts below the top steel frame. My wife wanted ours deeper, so we have a "safety ledge" all the way around the pool that provides the dirt support for the wall frame, but then it drops off to give us a deeper tray. Our deep end is about 52" deep, but AquastarMI has told me that some people go a full 8' deep.
You can see the "tray" with safety ledge on image 28 and 29 of page 1. By the way, we love the 2" foam bottom. It feels great on your feet. Nice and soft, but it doesn't "ding" like a sand bottom. My only problem with using foam board is that there are seams between each 4X8 sheet where the vinyl falls slightly lower than the main bottom. I had thought that using spray foam between the seams would make them invisible to the vinyl, but the spray foam is very soft and compresses. This makes a seam for trapping dirt, bugs, etc. In a way, this might be good because when I vacuum the pool I just go to the seam and suck it clean. Since I have no experience having a pool without this seam, I don't actually know if this is good or bad.
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