funny, it doesn't look very deep in that pic, but it is 3 ft.
I had to build up that end quite a bit w rock to level it to the other end you don't see in the pic, in other words the end you see is raised up past the soil line by a good foot.
I put the blocks in for the fish to hide and to set the pump on so if it malfunctions it won't drain the pond entirely and kill everything, learned that the hard way
as I do most things