What happened in this story?
"Through the Tunnel" by Doris Lessing is set in an undisclosed location, but it is a beach resort where Jerry and his mother have holidayed on various occasionas. There are two beaches - the "safe" beach which is described very domestically where his mother spends her days, and then a "wild bay", where Jerry goes on the second day by himself. Going there, and swimming in the more dangerous water, Jerry sees a group of older boys who are playing together. They begin diving off rocks into the sea. Then they begin to play a more dangerous game, whereby they dive into the sea for a very long time and then come up on the other side of a big dark rock. Jerry tries to follow them but is unable to. He discovers that there is a hole in the rock that the boys have swum through and determines to swim through it himself. He starts a rigorous regime of training by practising holding his breath and extending the time he can stay underwater for. His mother becomes concerned by how seriously he is training, especially when he comes home with a nosebleed. Jerry however improves his time and determines to achieve the feat on the day before they leave to go home. The day comes and in spite of some problems, Jerry achieves the feat and comes up. He goes back to his villa a changed boy, having symbolically gone through the tunnel from childhood to manhood.