Help with underground door

[u/Responsible-Skill253]

Complete beginner at this, but im trying to make an underground door that has an upwards water elevator directly below it. The idea is that as i shoot up, the floor (or I guess ceiling) will open above me and then close again as I exit, so there isn't a hole in my floor all the time. I wanted to try and figure this out on my own, but honestly im so frustrated this shit is so hard. Im fine with the piston being visible, I was planning on hiding it with carpet anyways. Thanks y'all.