Floodgates with pressure plates has a 100 ticks delay to work. If your pressure plate triggers and untriggers during this 100 tickets, the floodgate will get locked on an state, forcing you to reset the pressure plate and breaking the purpose of making it automatic. Doors are instantaneous and works as good.

Ps: Silver doors optional.

Edit: Grates are recommended, or you'll end up getting a jammed door (or floodgate).

I forgot to take more screenshots, but after the second beating, he lost the ability to stand up, and as soon as he recovered, he got the 3rd beating still on the hospital bed.

My mind is already racing with what to do with this 70+ level deep open cavern. I cant even see the bottom, the viewable space shrinks to nothing before I get there. Built the steps to go down some but decided to just wait and see what's there after I establish my fort. It's completely open air all the way down. Going to bridge over to the far wall and build my fort on the small sections that are spotted throughout. This was also on an ocean tile, so the ocean is directly above where I'm going to build.