The floors themselves.. is it possible to strike through them? I don't imagine they are all that thick, so the plan that Luffy has gotten into his head is to break through the floor they are being kept on and get themselves to a lower level where the doors and walls aren't as tightly guarded or watched over. The idea is that the guards and staff won't be expecting it, and it's also more in character for Luffy to try something like this.