This vintage bathing suit probably dates from the 1920s or early 1930s.  It is a skirted one piece design, with diamond crotch gusset and buttons at both shoulders to get it on.  It has the number 343 chainstitched on the front, and the number 129 stamped on the back.  Race numbers?  Rental numbers?  The buttons are missing, there is a rust stain on the shoulder and light staining throughout.

Chest (unstretched): 20″ (doubled = 40″)

Chest (stretched): 24″ (doubled = 48″)

Waist (unstretched): 18″ ( doubled = 36″)

Waist (Stretched): 22″ (doubled = 44″)