A boater is a stiff, flat-topped straw hat with a ribbon around the crown and a flat brim.

Boaters became extremely popular in the late 1800s and early 1900s, when gentlemen wore them during the summer months or at outdoor social events. You might see them in old photographs of barbershop quartets, since the striped style became associated with that classic American musical tradition. The hat appears in many vintage photos of people at picnics, on riverboats, or watching baseball games.

While boaters aren't common everyday wear anymore, they still show up at certain events. Some schools use them as part of their uniforms, and they're traditional attire at specific British events like the Henley Royal Regatta, a famous rowing competition. The word boater can also simply mean someone who boats: a person who sails, rows, or travels by boat for fun or sport.