When I first photographed leopard seals back in 2006 for National Geographic, I ended up being force-fed penguins by a massive female seal. I gave a Ted talk on the encounter titled “Tales of an Icebound Wonderland” and her surprising generosity forever changed the way people perceive these extraordinary animals. Ten years later, I had the opportunity to return to Antarctica to relive the experience. Within minutes of slipping beneath the surface, I was welcomed by a playful seal opening its mouth wide against the dome of my underwater camera housing. This may seem like an act of aggression, but I could clearly see curiosity reflected in the seal’s eyes. Far from the vicious predators people...