The most modern beach waves we're seeing look less ropy than the ones of the past. It's the model-off-duty hair of your dreams, and it's created with a flat iron. Anthony Cole, who did the hair on behalf of Sebastian for the Christian Siriano show, explained his method:
"Bend the hair as it naturally goes, and clip it [with the hair iron]. Start making little S shapes as [you feel it through the iron], leaving the ends straight. It's a flatter texture — rather than round or big. When we [usually] curl hair, we're used to taking sections that are horizontal. Instead, curl it vertically, and then feed it through the iron so it stays flat."
For an extra undone mane, comb the cooled-down waves through, and mist with sea-salt spray.