We have an 18' diameter above ground pool.
I have levelled a spot for it.
In our previous place I used landscape fabric under it with a brick patio/walkway around it that I would rearrange near the edge of the pool as it is impossible for me to get it in the exact same spot every year.
I do take it down for the winter.
We have moved and now what I am looking for is a way of finishing a flat are for the pool to sit on.
I think some sort of large mat which would allow water to go through it would be best. Then I would use brick or 4x4 for a border to mow against.