http://www.ebay.com/itm/271225359270
This vintage swimsuit was made by “Ocean”. This company was originally known as Ocean Champion, and later “Ocean Pool Supply”. This company was the official supplier of swimsuits to the United States Olympic team for most of the first half of the 20th century, before being supplanted by Speedo. This is one of their later production models, in their lower waisted “Ocean Brief” style. These suits were made out of two independent layers of nylon, with a drawstring waist.  Compare to an earlier Ocean Champion suit (here), and a similar one made by Dolfin (here)

Waist (unstretched): 15″ (doubled = 30″)
Waist (stretched): 19″ (doubled = 38″)
Side Seam: 6″
Rise: 10-1/2″