This is actually rather a difficult question to answer, because I think that a number of the factors that made Jerry decide to swim through the tunnel were unique to his situation and background. Let us note that Jerry has only his mother to look after him, and his mother certainly is struggling to let him have the freedom and independence that he needs so that he can grow up and mature by himself. Note how the mother is described:
He was an only child, eleven years old. She was a widow. She was determined to be neither possessive nor lacking in devotion. She went worrying off to her beach.
She is clearly finding it hard to get the balance between loving Jerry yet giving him space, and Jerry's lack of a father-figure would give him the desire to prove himself in reaction to his mother's over-protective love. Thus we can see that Jerry's decision to swim through the tunnel can be explained in relation to his personal circumstances.
For me, I grew up with both my parents and so probably would not have felt the need to prove myself in such a dangerous way. Having a father who encouraged me and my brother to be independent and to mature from an early age would have meant that I would not have felt the need to swim through the tunnel.