I water proofed under my deck before I knew what bonsai was and use it as a recovery place for trees. Since the accumulation of too many trees and winter coming up quickly I decided to turn it into a make shit cold frame.
I originally made a small sink in cold frame that sits next to the stairs and can be seen from under the deck at eye height. Added some pictures in case it gives anyone ideas for their space. this year it is more functional than pretty I will tackle the aesthetics next year if it works out well.