How deep is your pool? Above ground pools are usually quite shallow. What are you trying to accomplish, besides just having fun?
You COULD put a plant box outside the pool, and vault into the pool with a big splash ... but WHY???
Do you mean planting the pole OUTSIDE the pool and then landing INSIDE the pool, or if you really mean planting it INSIDE the pool, then exactly what do you mean? Standing on the edge of the pool, then swinging into it?
My gut tells me that this is a bad idea. Above ground pools are not only shallow, they're also quite fragile.
Kirk