I was stationed in Antarctica from 87 to 92, both with the Navy, and the National Science Foundation, in that time we had one incident. One of the research assistants was taking samples when a leopard seal lunged out of the water and grabbed her. Startled, it flopped back into the water. She screamed, and fell back. She was bruised around the knee, and shook up, but all right. It should be noted that she was wearing white bunny boots, (a vapor barrier extreme cold weather boot), and black wind pants. The theory is that it mistook her, crouching, viewed through the ice, as a penguin.
Other than this one time, they generally ignored us. I got to dive twice while I was there, saw one once, it never gave us a second glance.
The motto is accurate; 'It's a harsh continent.'