A surfboard was a flat board used in the Earth sport of surfing.
In the late 20th century, one brand of surfboard was McCoy. (VOY: "Future's End")
The Earth colony ship SS Mariposa, which launched in 2123, carried twenty-five Banzai Pipeline Surfboards. (TNG: "Up The Long Ladder")
In 2368, Geordi La Forge compared the flight of a starship on soliton waves to riding a surfboard. (TNG: "New Ground")
In a stage direction from the final draft script of TOS: "Miri", "some wild looking surfing boards" were said to be included inside Biggs' toy store.