To explain in detail I wanted to make an ocean camp but instead of building a bridge from shore over to the designated spot I would use a tree deeply rooted into the seafloor that is really really tall so that I can stand on the branches and build support off this tree using my knowledge of tree fort,
What I got was no ocean tree as all the modified trees spawn on the beach and the first one I found was unable to chopdown.
so I booted up fort mode and try my hand at the task again.
which lead to finding out my Sea Caps are insane
the root is protected by the Tree's shroom cap which prevents the dwarves from cutting it, also it has a top that basically a huge hole even though the bottom is solid.
so I found a thinner exposed core Sea-cap and well this happen.
then my second attempt at chopping a sea cap crash the game.
deciding to dive back into DF arena mode to fix some Adventure reactions I ended up breaching the arena ceiling through designating a giant Stairwell to unseen and building a bunch of walls and ramps on the arena top level and ending up causing the game to build a huge sealed off floor from that. but some how the stairwell broke through that wall and it lead to being able to spawn a dwarf on that stairwell.
so the floor on this space zone is impossible to move on unless you jump around or you ride on a minecart.
I thought during the time It was a complete empty zone before making the gif and reaching 'a planet...'
so yeah got to explore the great unknown void and looking for a way to build on it.