How is the tunnel in Doris Lessing's "Through the Tunnel" a symbol?

Clearly the major symbol in this story, the tunnel and
Jerry's passage through it, is linked to the theme, which is the transition from the
state of being a child to being an adult. What is important to focus on is how the theme
is developed through the use of the symbol of the tunnel in this excellent short story.
By the end of the story Jerry has gone through a journey from childhood to manhood,
symbolised most stridently in his journey through the
tunnel.

At the beginning of the story we are introduced to
a character who is on the cusp of adolescense, and very clearly feels responsible for
his mother due to their enforced intimacy. Yet despite his feelings of responsibility
towards his mother, he nonetheless feels drawn to the "wild beach", which is away from
the "safe beach" and his mother's attentive care. The wild beach here can be said to
symbolise independence and life away from the protection of a parent figure - note how
Lessing describes the two beaches to draw out this
comparison.

His discovery of the tunnel and the challenge
that the French boys set him through swimming through the tunnel spur Jerry on to train
hard and eventually succeed in his attempt to go through the tunnel. Although certainly
at the beginning of the story it is Jerry's need to be accepted by the older group of
French boys that drives his desire to go through the tunnel, it is interesting that at
the end of the story he no longer feels this is the case, as he is happy to go back home
and spend time with his mother. This indicates that the tunnel was more about a process
of self-acceptance and doing something to show he could do it for himself rather than
for any other reason.

His relationship with his mother
likewise has changed by the end of the story. Jerry deliberately witholds his triumph,
only relating his ability to hold his breath. The dramatic irony in his mother's
response ("I wouldn't overdo it, dear") indicates the independence that Jerry has
achieved in his journey through the tunnel - he has now entered an arena where he has
secrets from his mother and is able to engage in activities, dangerous activies, away
from his mother's protection.

Clearly this story is about
adolescence and the steps that one boy take to become a man, at least in his own eyes,
and to emerge out of the other end of the tunnel of adolescence. This is how Lessing
uses the tunnel in this excellent short story.