It was just before three o’clock on Sunday morning in Tunisia when the 18-year-old swimmer Ahmed Hafnaoui won a gold medal in the 400 metre freestyle at the Tokyo Olympics. But it seemed as if the whole of Tunisia had stayed up to watch. Videos of his coach’s celebration dance and his cheering family went viral. Hafnaoui wasn’t expected to win. He had barely qualified for the race and was competing in an outside lane, which may put swimmers at a slight physical disadvantage (from the waves splashing off the wall) as well as a psychological one. He also comes from a country of empty swimming pools.