Rio de Janeiro (dpa) - Athletes, fans in attendance, and people around the world watching their colour TVs couldn‘t quite believe their eyes when, on Tuesday, the water of the pool for divers had turned green.Organizers tried quickly Wednesday to assure everyone that the water‘s just fine - health-wise - but admitted they did not know what happened or what caused it.The images were all the more jarring since the swimming events pool was the usual clear-blue colour.