Humpback and Antarctic minke are the two you are most likely to meet. Fin whales and orcas are possible and can be locally common. Everything else is rarer than the brochures imply.
Ranked honestly by how often you would actually see them:
- Humpback, the most frequently encountered large whale, especially later in the season
- Antarctic minke, regular, and often around ice and narrow channels
- Fin, possible, sometimes locally abundant around the Bransfield Strait and Scotia Sea
- Orca, possible any time, but highly localised. One voyage meets a big active group and the next sees none
- Blue, southern right, sperm, beaked, rare to exceptionally rare. A major expedition event, never a reason to book
Minkes are smaller and faster than humpbacks and surface briefly, which makes them harder to photograph and harder to identify. They sometimes show curiosity around ships and Zodiacs, though any close approach has to be the whale's idea.
Fin whales are the ones you tend to see during an open-water transit rather than on a sheltered Zodiac cruise, so keep binoculars on deck.
People mistake large fin whales for blue whales fairly often. The identification comes down to body colour, dorsal fin shape and surfacing pattern, and a good naturalist will be careful about it rather than giving you the answer you want.
Krill moves, and whales follow krill. One departure gets extraordinary encounters and the next one, same route, same week of the season, sees fewer.