BERLIN — Yusra Mardini, an Olympic swimmer, was an hour and a half into her first training session of the day, butterfly-kicking down the length of a pool with a yellow rubber ducky balanced on her head.
Other young swimmers shared the lane, but Mardini, 18, kept her own pace, darting down the center, emerging at the edge of the pool from time to time to exchange the ducky — used for balance training — for a snorkel or a kickboard.
Mardini has been practicing since October at the training center for Wasserfreunde Spandau 04, one of the oldest swimming clubs in the city.