Cow, a one-year-old female elephant seal, looks out from the water in her rehabilitation pen at the Marine Mammal Rescue Centre in Vancouver. (Vancouver Aquarium)

An unusual passenger caught an early morning ferry ride to Vancouver Island Friday morning, heading for a beach on the southwest coast Vancouver Island.

The passenger was Cow, a 182-kilogram northern elephant seal, who picked up her nickname while recovering at the Marine Mammal Rescue Centre in Vancouver.

Cow was heading to the seashore west of Victoria to be released into the waters of the Strait of Juan de Fuca, after spending the past six weeks in Vancouver being nursed back to health by marine mammal specialists.

The one-year-old female was first spotted on Rainbow Beach in Esquimalt's inner harbour six weeks ago. At the time she was shedding, but was also diseased and in danger of dying from what Vancouver Aquarium staff eventually diagnosed as northern elephant seal skin disease.

She was rescued by specialists and transported to the aquarium's Marine Mammal Rescue Centre where she was treated with antibiotics.

Rescue co-ordinator Lindsaye Akhurst said Thursday a few scars from skin ulcers remained, but a veterinarian had determined Cow was healthy enough to return to the ocean.

In November, a 2,000-kilogram adult male elephant seal carcass washed up near Nanaimo on the east coast of Vancouver Island.

Elephant seals were once native to the West Coast, but were hunted to near extinction 100 years ago. In recent years, the animals have been observed at Race Rocks near Victoria, and have re-established large breeding colonies along the California coast.