As I plunge at last into the icy ... water, we’re wearing and carrying 200 pounds each. It feels like we’re learning to dive all over again. Moving is a struggle, swimming almost impossible ...

They became heavier and more streamlined, with dense bones that help them dive ... water with precision and grace.

Penguins first evolved the ability to dive, like a puffin ... Those may no longer be needed as penguins forage in cold, salty water and typically swallow prey including fish, shrimp and squid ...