Yup. Amazing that cultures centred around rivers would have floods in their myths and legends!
More hydroplate fun.. The layer of rock enclosing the layer of water would have to be perfectly sealed across the entire planet. No earthquakes before the flood then, and no asteroid strikes. Good thing the flood happened when it did since we'd have caused it later ourselves by drilling into the crust looking for oil or water or just wondering what's down there.
For a crust riding on a layer of water, there can't be any mountains either, since a mountain would weigh down that part of the crust and cause it to bend and break, releasing the flood early. So no mountians (despite the flood account specifically mentioning mountains).
How do you keep the core of the earth from crashing into the crust riding on the water? If they crashed it would release the flood early. The moon causes huge tides, it would cause turburlance in that layer of water too.
Plus there would be evidence of the chamber that used to house the water, even if it's just a horizontal fault line with some left over water in it, but there's no evidence.