The crew spends nine days on the sub. They use a loudspeaker to call out to any people who might still be alive on shore, but a lone dog is the only living creature they see. From the sea, everything on land looks the same except for the lack of people. The city of Cairns is full of sunshine, flame trees, and pleasant shop windows—but a complete ghost town.
Peter suggests writing a history of the war, but John questions why they should bother when no one will be left to read it. Peter would still like a history because, even though he was in the war, he does not know a thing about how it started or escalated. John knows that 4,700 nuclear bombs were dropped in the war. Dwight states that a month before the war he attended a meeting in which American intelligence officers spoke about a potential conflict between China and Russia. The Russians wanted to take over Shanghai. The Chinese, for their part, wanted to bomb Russia's industrial cities to gain more land for its crowded population.
No one thought the rest of the world would react to a war between Russia and China, but the small country of Albania started a war on another front, and bombed Naples. Then a bomb dropped on Tel Aviv, but no one knows who was responsible for that one. The United States and Britain then flew a demonstration flight over Cairo. The next day, Egypt bombed Washington and London. The United States mistakenly thought the Egyptian bombs came from Russia, and therefore bombed Russia in retaliation. John blames the war on the fact that the atomic bomb became so cheap to produce that every country could possess one. Dwight argues that the trouble came from Britain and Russia supplying the Middle East with long-range airplanes.
Many countries' top statesmen were killed in the war, leaving the command in the hands of junior military officers, who continued the war until all the bombs were dropped. Dwight, Peter, and John discuss what they would have done if they had been in the junior officers' position. Dwight admits that although he would like to think he would have negotiated, he probably would have done the same thing they did—continue the bombing.
John says that they have six months left before the radiation arrives, and he urges them to make the most of it. Peter responds that he would rather be working than doing anything else. He still cannot believe they are all going to die. John accuses Peter of having no imagination. Peter agrees he does not have an imagination, but says that he never had to imagine the end of the world before. Dwight pauses to think of the beautiful landscape he has seen from the shore and says, "Maybe we've been too silly to deserve a world like this."
When they arrive back at Melbourne, they give their report. They have no good news—only John's radiation readings. Dwight suggests sending someone onshore during the next expedition. Peter phones Mary to tell her that he is safe, but says that someone aboard caught the measles and that it is potentially contagious. Mary worries that baby Jennifer will catch the measles.
The next day, Peter and John go to the Pastoral Club, an exclusive, formal social club in town that follows the English tradition of gentlemen's clubs. John has always wanted to join the expensive Club, and he has decided he is not going to wait any longer. John and Peter sit with Douglas Froude, a former Lieutenant General and John's great-uncle. Before the war, Douglas's doctors warned him not to drink too much. Now, however, Douglas comes to the club three days a week to drink its vintage port wine—3,000 bottles in the club's cellar and only six months to go.
The radiation is continuing to move south at a steady rate. One day, Peter, Mary, Dwight, and Moira picnic on the beach and go sailing. Moira tells Dwight that she saw the photo of his family in his quarters on the submarine. Dwight talks about his family as if they are still alive, and Moira realizes he has not accepted their deaths.
Just as in Chapter One, Shute uses an understated tone to describe the radiated areas of Australia. The beauty of the land and the lack of obvious physical destruction makes it even harder to accept the death of the population. When Dwight thinks about loss of life in the lovely landscape, he observes, "Maybe we've been too silly to deserve a world like this." For the first time in the novel, a character uses the collective "we" when talking about the cause of the war. Rather than blame the destruction on distant countries, Dwight holds himself and all other humans responsible for the waste and destruction of the beauty of the earth. Many environmentalists embraced On the Beach because of its insistence that everyone is responsible for the stewardship of the entire planet. The serenity of the irradiated towns the crew sees is even more disturbing because it means the residents died tidily, without resisting their fate. Ever the realist, John cannot resist saying that the dying people acted like animals, crawling into holes to die—in his view, showing themselves to be undignified, even pathetic creatures.
The faults of human beings become even more apparent when the men discuss the causes of the war. Peter fought in the war for a little while, but admits he does not know a thing about its causes or course. Mindless obedience in the military, on the part of both leaders and soldiers, appears to be one of the reasons the war spiraled out of control. Dwight admits that he too would probably have behaved like the rest of the junior offices left in control, using every last bomb—he was trained to be obedient, not diplomatic. He would have defended his national honor without thinking of the moral consequences of his actions.
Optimists during the Cold War believed human beings to be too rational to ever use nuclear weapons. Even Peter, living during the aftermath of the nuclear war, still cannot imagine that humans are capable of such a thing. Shute realizes that most of his readers probably are similar, simply unable to truly believe such a war is possible. On the Beach is Shute's attempt to provide our imagination for us. He creates a scenario in which nuclear war is possible, especially if the weapons fall into the hands of a small group of irresponsible, irrational people. Even though many countries participated in the war, John blames it on "the little ones, the Irresponsibles." He points out that nuclear weapons became so cheap that small countries could build them; Dwight, however, is quick to point out that the large countries also played a role. Russia and Britain sold long-range airplanes to Middle Eastern countries, and therefore, also have to take partial responsibility for the war.
The men aboard the ship struggle to figure out how to fit their present situation into a historical context. After they die, no one will be left to read their history. They cannot decide if there is any point to recording current events for posterity—a debate that raises the larger issue of the purpose of historical records in the first place. If history is written to provide knowledge for future generations, then it could be seen as a waste for them to record the history of the war. However, Peter seems to want to read a history, to himself understand the war he just experienced.