How high is Snafell?
How long does Axel think it will take to reach the true center of the earth?
How do Axel, Otto, and Hans reach the surface of the earth?
How do Axel, Otto, and Hans decide to deal with a boulder blocking the passage?
What is unusual about all the fish caught during the seagoing expedition?
What is the name of the guide who accompanies Otto and Axel on the expedition?
Axel struggles the most with trying to explain __________________ in the underworld.
What is constructed to cross the underground sea?
In what year does the novel take place?
What is the source of eider-down?