Most people don't know what a narwhal is, and because they are such a fascinating creature, I think everyone should know what a narwhal is. Narwhals are a species of whale, so they are also mammals that breathe air. They live in arctic waters of Canada, Greenland, and Russia mostly. Full grown they are an average of 15-20 feet long. Narwhals have a UNICORN HORN! Unlike a unicorn (sadly), they DO exist.