Question

Why is "Through the Tunnel" a coming-of-age story? Because Jerry goes through a rite of passage in "Through the Tunnel," the story is classified as coming-of-age story. In "Through the Tunnel," swimming through the tunnel is important to Jerry because he wants to impress the older boys. In "Through the Tunnel," Jerry does not challenge himself. In "Through the Tunnel," Jerry does not feel as emotionally close to his mother as he does to his father.

Answer 1

Jerry does not challenge himself..... hope this helps

Answer 2

'Through the tunnel is a coming of age story BECAUSE JERRY GOES THROUGH A RITE OF PASSAGE IN THROUGH THE TUNNEL.
A coming of age genre in literature is one which focuses on the growth and development of an individual from a child to an adult. 
In through the tunnel, Jerry has to swim through the long passage of the rock tunnel in order to prove that he is no longer a child but a man, who is fearless and has all the qualities expected of a mature man.