Hi dan the concept is not new. Couple of them around. You can fly in the rain but there is still risk of failure and you have to take care of the motors afterwards, ball bearing will also not be happy etc.
They are fun but i don't really see the point of them. Some land them in the water but, think of landing them in open water with waves landing and taking off again too risky !
Maybe with a go pro on them in a water proof case it could be fun and get some cool footage !
Boris