Axel wants to immediately begin exploring the newly discovered gallery, but Otto suggests returning to Hans first so they can bring the raft with them. The entire group returns to the tunnel. However, their progress is soon blocked. They conclude that there must have been a rock fall at some point after Saknussemm passed through. Axel gets the idea to blast their way into the tunnel by using their remaining gunpowder. They prepare everything and decide to wait until the following morning to set the charge. 

Axel volunteers to light the match and run back to the raft as he calculates that there should be 10 minutes before the explosion. The rock face begins crumbling, and an abyss opens up. The sea rises in one huge wave, sweeping the raft along into the chasm. The three men hold hands so as not to fall overboard.

At some point, Hans succeeds in lighting their lantern, and Axel realizes they are falling down a wide gallery. Their descent into the abyss continues for hours. At one point, Axel realizes that their supplies have fallen overboard and the only food left is some meat and biscuits. Eventually, the lantern dies out, leaving them in complete darkness.