The whale shark (Rhincodon typus) is a slow-moving filter feeding shark and the largest known extant fish species. The largest confirmed individual had a length of 12.65 metres (41.50 ft) and a weight of more than 21.5 metric tons (47,000 lb), and there are unconfirmed reports of considerably larger whale sharks.
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Seas, Nature - Birds and Animals
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By: Mike1989
There's how the photos are taken underwater.