Alex Mustard's Image

Alex took this shot in open water in the Caribbean Sea, off Mexico's Yucatan Peninsula, while swimming among a huge aggregation of whale sharks.

The sharks were feasting on millions of tuna eggs. One picture he had decided on was a backlit silhouette that would show the bow waves generated by these enormous animals - the world's biggest fish - as they push through the water, scooping up food in their giant mouths. When he spotted the fin of an approaching shark with the sun behind it, he dived down, held his breath and waited for the eight-metre animal to pass overhead so he could shoot it backlit, with the sunbeams spearing into the water along its flanks. 'As serene as the moment looks,' says Alex, 'I was bursting for air. The combination of excitement and awe didn't help, or the fact that I had five metres of water and a shark between me and the surface. But the result was definitely worth it.' The tourism that has developed around the feeding aggregation is also worthwhile. It's put a value on keeping the sharks alive rather than as fodder for the shark-fin industry (a whale shark fin can fetch between $10,000 and $20,000), giving the sharks in Mexican waters a brighter future.