In literature, external conflict refers to the struggle a character has with nature or another character. The opposition that the character experiences, adds to the drama. Internal conflict refers to a struggle that exists within a character's mind. The resolution of such a struggle leads to a new understanding or...
a dynamic change in the character.
In the story, Jerry's external conflicts are firstly with his mother that initially wants him to be at her side. She is clearly very protective of him since she is a widow and he is her only child. Jerry, however, wants to enjoy greater freedom but does, out of duty to, and respect for, his mother acquiesce to her request. Jerry felt quite remorseful and apologetic when his mother asked whether he wanted to be somewhere else and not with her and replied that he did not.
Jerry's mother does realize, though, that he wants to be somewhere else and later allows him to go to the bay where he longs to be. This temporarily brings to an end this conflict. The conflict expresses itself again later, though, when Jerry desperately wants to swim through the tunnel. His mother is clearly concerned when she notices that his nose was bleeding and tells him to spend the day with her, which he does. The next day, however, he leaves early to avoid her scuppering his plan.
A second external conflict Jerry experiences is the obvious contrast between him and the boys he meets. They are natives from the area and that, on its own, is conflicting. Furthermore, he cannot understand their language. Thirdly, they perform a feat that Jerry obviously cannot and they later leave him.
In addition, Jerry also struggles against the elements, the sea and especially the conditions underwater, when he attempts to swim through the tunnel. He discovers that it is narrow and later finds, almost to his extreme detriment, that the tunnel is quite lengthy. He does later successfully negotiate his way through it eventually and resolves the issue.
Jerry's internal conflict, firstly, arises from his mother's wish and what he wants for himself. He has to choose between doing what he wants or being obedient. At first, his guilt is what compels him to stay with her. He finally resolves this conflict by telling her that he longs to be elsewhere and she allows him.
Secondly, Jerry is caught between deciding whether he is going to continue risking his life to get through the tunnel or give up. He decides to take the risk and is successful. Thus resolving that conflict. The reason for this inner turmoil is informed by the embarrassment Jerry felt when the other boys left him, as if he was not worthy of their attention. He felt much the same as he did when his mother rewarded him with 'grave, embarrassed inspection' when he clowned around, seeking her approval.