This presentation by Paul Nicklen is possibly the best TED talk I've watched - - funny, fascinating, well-delivered, and supported by tremendous photographs. Among the interesting factoids: The ice he regularly dove in was so cold that he typically vomited each time he hit the water. National Geographic's informal motto is "we publish photographs, not excuses." And unless I heard wrong, one of the whales pictured in the video is believed to be 250 years old.
But most of all, the leopard seal stars as a fearsome (as in, sometimes they eat people), but sometimes charming creature.
*Buy National Geographic back issues at eBay.