After a far too long swimming competition of two of my daughters, we waited for the results and the medals. The water became quite very quickly and I saw this reflection.
The reason we spent too much time in the swimming pool, was that the water was 31 degrees Celcius, where the max is 28. When they cooled it down to 30 they decided to let it start anyway. I believe for some reason Nieuwegein has an exception to may have competitions up to 30 degrees.