Big Wednesday (1978)

Directed by John Milius and starring Jan-Michael Vincent, William Katt and Gary Busey, Big Wednesday follows three California surfers from the carefree early 1960s through adulthood, military service and the changing surf culture of the 1970s. Their friendship is tested by the Vietnam War, relationships and the passing of time before they reunite for a legendary swell in 1974. The film became a cult favorite within surfing culture after an initially unsuccessful theatrical release.

Från IMDB:
Character study about the lives of some California surfers from the early 1960s to the 1970s as the Vietnam War interrupts their carefree life.