Every booking inquiry that lands in dive operator Richard Swann’s inbox these days carries the same undertow of anxiety. Before his clients commit to a dive trip off Kota Kinabalu, they want reassurance: are Sabah’s reefs still worth the journey?It is a question that would have seemed strange a generation ago, when the waters off Malaysian Borneo were simply assumed to be among the finest on Earth. Now it is one of the first things visitors ask and the answer, according to a new environmental...