In the Time and Tide area, how can I go right on the procedurally dropping floors?

On level four, through the Time and Tide portal, how do I go right when I have to move across the long open/shut floor thing? Do I just have to be fast and run over there before those re-open? I've been trying that, and it doesn't seem to be working. Looking at the map, it seems to just be a 1x1 room. What's over there?

There is a hidden switch in the right hand wall as you start going down the collapsing hallway, which slides open a section of wall a bit further ahead on the right, letting you get back there and grab the Chitin Mask from a wall nook.

I don't remember the exact square which has the switch, but as you start going down the collapsing hallway, it'll be a loose rock in the wall on your right. I've marked roughly where I think it is on the map (I might be off by a square), as well as marking the wall section which slides open and where the mask is contained.

in the first opening to the right there's a hidden button that opens an area to the right a bit later, that gets you a secret (just fyi, not needed to continue but secrets are cool) After that, continue on and in the second to last step you turn yourself left and see a floor switch at the end, throw a rock and that should let you continue to the exit