Dan, I have a couple submerged islands. I think the normal depth for most lillys is about 4' with a 18" secchi reading. Clearer water and they can come up from a LOT deeper. I have a tubidity problem as I have good sealing clay but it likes to suspend so I plan on putting lillys on the islands this spring. I also found on ebay packs of 500 tropical lillys and lotus that won't survive winter that I plan on planting as well. It blows me away that it costs me $9 to ship a package across town but he can ship his seeds half-way around the world from Thailand for $5. BTW the seeds were $2.