There's a serenity in the silence under the water.
The free diver, Michaela Werner, glided close to the bottom of the pool, taking long steady strokes. She swam the entire length of the 25-metre pool underwater, before coming up for air for less than 10 seconds at either end. In that short time, her coach might give her the lap count before counting down from seven, six, five, four, three ...
