Journey to the Center of the Earth Lesson Plan

What near fatal error did the Professor make in the early stages of their decent? Could it have been prevented?

Professor Lidenbrock is faced with a decision when they come to a fork in the tunnel; take the eastern or western route. We’ve seen already that the Professor is a man who dives in without much thought (ex. the journey as a whole), so it keeps with his character to choose one path and stick to it without much second-guessing. Their journey down this tunnel proves very nearly fatal when they run out of water, and Axel barely makes it back to the fork alive. What might the travelers have done to prevent this? Perhaps scouting out each tunnel before...