In the beginning of On the Beach, Moira is an alcoholic, constantly drinking to forget her impending death and the fact that she will not have the opportunity to pursue her dreams of traveling outside Australia, marrying, and having a family. Bored with the despair and tedium of her life, Moira feels like she is "waiting to be hung." Whenever the morbid reality becomes too real, she tries to escape into a world of wild partying, dance, and drink. Her friendship with Dwight is key to her transformation. While Moira's liveliness distracts Dwight from his worries, he helps her find a purpose and direction in her last few months. He encourages her to take secretarial classes as a means to keep busy and to improve herself, even though the lessons will never come to any practical use.

When Dwight and Moira first meet, she is intensely flirtatious, but she stops making advances once she realizes he will remain loyal to his wife. In the process, Moira falls in love with Dwight even though she knows a romance is impossible. In other circumstances, when Moira would have had time to start a family with Dwight, she says she would have tried every dirty trick in the book to get him. Now, however, when there is so little time left, she decides it is not worth sacrificing his or her dignity to start an affair.

Shute writes about both the danger and necessity of scientific discovery and knowledge. Knowledge can be dangerous when it is used toward evil ends, such as the creation of weapons of mass destruction. It is dangerous to preserve and pass on this kind of knowledge. Moira brings this issue to the surface when she mockingly asks if the Australian historians will preserve knowledge on how to manufacture a cobalt bomb. Knowledge is also necessary to help people understand the impact of technology on their lives. Peter talks about how newspapers might have saved humans if they had published articles that educated people about how to create a more peaceful world. Since there are no newspapers passing on this knowledge, Shute writes On the Beach as an educational resource. In this light, the novel is meant to have impact as a means of preventive history.

Shute depicts a society in love with technological creation even though technology has caused the society's destruction. Shute does not mock this relationship, but simply states that it exists. Indeed, characters throughout the novel adore technology and machinery. Peter is greatly impressed with the workings of the U.S.S. Scorpion. Dwight shows off the ship's technology to Moira during her tour. When Lieutenant Sunderstrom is on Santa Maria Island near Seattle, he spends some of his precious little time admiring the electric transmitter that has functioned so well on its own for two years; he even looks for the name of the company that manufactured the machine. Even Yeoman Swain, though amid the signs of the death of his family and hometown, remains happy in his last days because he has access to a car and motorboat. No one is more obviously in love with machines than John and the others racing in the Australian Grand Prix. At the racetrack, both drivers and spectators are concerned more with proving the efficiency of their machines or admiring the cars, respectively, than their personal safety. Just like the people who developed and used the atomic bombs, the drivers are ready and willing to use technology, but are not willing to take responsibility for their potential dangers.