Good illustration!
I think the key to understanding the danger is to see the first (or last, in their case) restriction where it says “Passage is too narrow for diver to wear oxygen tank”.
Depending on how narrow and how long this passage is, is it possible to widen, or do they just need to bring them here, and figure out the quickest way to get them through?
“Passage is too narrow for diver to wear oxygen tank”
I noticed that too. Once upon a time I was a girl scout. Even if my troop leader were Jesus Christ himself, I would not have followed past that first narrow passage.
Brave boys. Brave rescuers. Praying for them all.