They crawled along the tunnel in the dark for longer than Gerard was comfortable with. At this distance, fresh air would be harder to come by. That would mean lack of oxygen, and death. When he brought up his concern to his partner, Astrid shrugged and reminded him that was what their breathing tanks were for.
When they finally reached their destination, they carefully lowered themselves into the cavern, so as not to disturb more than they had to. The contents had to be in pristine condition for when they were discovered.
"Why now? Why couldn't we have gone back further?"
"This is as far back as we can safely go. Before