35 feet is large, but not so large that it would guarantee certain death if we fell. How long are the ropes in our adventure packs? Would it be safer to send one of us across with a rope to drop down on the other side, and hoist to the cavern floor from our side? I'm sure that those mushrooms represent some kind of danger - poison, most likely, even if we don't eat them.
Whoever we send out first should be someone with good acrobatics/athletics, because I'm sure that's the roll they'd have to make if the rope bridge is a trap. Once again, I nominate Durzo.
