You're there to watch the animals' experience rather than make it about yours, and everything follows from that. Minimum distances apply, including the 5 metre guideline for penguins and more for nesting birds and jousting elephant seals. You never approach, even if an animal has approached you. If wildlife moves, you move. They don't adjust to you.
Guides enforce this and they're right to. Being asked to step back can feel like poor service in the moment, which is why good expedition teams explain the reasoning before you land rather than reciting distances at you on the beach. Understanding why tends to mean less friction on site.
A line one of our Arctic guides uses carries over exactly: a polar bear's life is not worth your good photo. However much you want the shot, the animal comes first, and it won't happen.
If a beach turns out to be too densely packed with wildlife when the guides scout it, the team switches everyone to a Zodiac cruise instead of landing. Read that as the system working rather than as a lost landing.