Research has shown that boys first start wearing tiny tailored trunks at the age of 13, usually because their parents have bought them.
As they move into their fashion-conscious teens, they usually switch to a longer length of trunk, often inspired by pop stars such as Justin Bieber, who opt for over-the-knee styles.
According to the research, which was carried out for the department store Debenhams, between the ages of 28 and 35 trunk lengths creep back up as young men look to show off their bodies in order to find a partner, with many aspiring to match Daniel Craig's appearance in blue trunks for a beach scene as James Bond in Casino Royale .
But from the age of 55 up to 59, swimming trunks often turn back into eye-watering briefs.
Ruth Attridge, a spokesman for Debenhams, said: "It was no surprise that most respondents referenced the pulling power of Daniel Craig's tight-fitting blue trunks as their main beach influence.
''However, when we discovered that even James Bond can't tear British men in their over-50s away from the skimpiest of bathers, we knew we had to start taking notes.''