http://www.ebay.com/itm/271234495023
This vintage swimsuit was made in the 1950s by Ocean Champion. Ocean Champion was one of the first companies to move away from wool and lastex blends, and into modern materials. At the point this suit was made, Ocean Champion was the official suit of the United States Men’s and Women’s Swimming and Water Polo Olympic teams.
As the box says, the suit is two independent layers, a trunk within a trunk. At this point, the manufacturer Ocean Pool Supply Co., was headquartered at 155 W. 23rd St., NYC.

Waist (unstretched): 13-1/2″ (doubled = 27″)
Waist (stretched): 17″ (doubled = 34″)
Rise: 14″
Side Seam: 10″