Southern Elephant Seal

The best place to grasp the scale of this animal is South Georgia, where thousands haul out on the beaches each spring. Bulls can be about 40% heavier than a male northern elephant seal and nearly twice the weight of a walrus, which makes the southern elephant seal the largest member of the seal, sea lion and walrus group, and the largest marine mammal that isn't a whale or dolphin. The proboscis that gives the species its name is put to loud use during the breeding season, when dominant males roar to hold their harem and see off rivals.

Smaller, more scattered colonies show up on beaches in the Falkland Islands and along the coast of Patagonia, useful stops if a voyage doesn't reach South Georgia's big rookeries. Further south again, Macquarie Island holds its own sizeable population, a reminder that this species ranges across the entire Southern Ocean rather than clustering in one spot.

Timing matters: the roaring, fighting spectacle of the breeding season is a spring event, while later in the season the beaches fill instead with seals hauled out to moult, quieter but still impressive simply for the sheer bulk involved.