McMurdo Sound is covered by sea ice for 10-11 months of the year. Drifting ice crunches up against the fast ice edge piling up angular ice blocks. Emperor and Adelie penguins can be seen in small groups taking rest breaks between group fishing excursions.
Predators are on the prowl for penguin prey.
In this photo, killer whales Orcinus orca cruise in a pack along the McMurdo Sound fast ice edge looking for penguin prey. Leopard seals Hydrurga leptonyx also hunt along the fast ice edge. The diver looks up at a sharp vee in the fast ice edge and sees swimming Emperor penguins. Emperor penguins swim in groups to increase their safety from predators. Emperor penguins eat fish, squid, and euphausid and amphipod crustaceans which they dive and pursue to capture at speeds up to 3.4 meters per second.