These orcas are spyhopping (taking a look above the surface). They do this while looking for prey and when looking for directions back out to sea.
p.s. The Antarctic is a gorgeous but fragile place, and Antarctic research scientists just released a study showing how the 40,000 tourists coming down each year have been damaging the ecosystem. Here’s a short video about this, despite the serious subject matter it’s very funny. The solution is to enjoy Antarctica from the comfort of one’s own home through awesome nature documentaries like these: Under the Antarctic Ice Beauty