https://slate.com/culture/2016/08/the-gymnastics-floor-at-the-2016-olympics-has-literal-springs-beneath-it.html
The floor at the 2016 Olympics measures 14-by-14 meters and consists of three layers. The “base layer” consists of “sustainably sourced plywood … over 2,000 optimally positioned springs to provide a consistent response.” Each spring measures 11.3 centimeters in height. The “intermediate layer” is made of “high-density interlocking foam panels giving increased levels of comfort and shock absorption.” The “performance layer”—the carpet at the top—“consists of several strips joined together by hook and loop fastener bands.”
