El Salvadoran surfer Katherine Diaz has been killed after being struck by lightning while training for a qualifying tournament for the Tokyo Olympics. The 22-year-old was struck just after entering the water on Friday at El Tunco Beach, about 10 miles (16km) south of capital San Salvador, local media reported. "Katherine embodied the joy and energy that make surfing so special and dear to us all, as a global ambassador of the sport," the International Surfing Association (ISA) said in one of many tributes posted on social media. Diaz had been preparing for the ISA World Surfing Games, which will…