In summertime, the Hudson Bay and Churchill River are alive with Beluga whales. These small Cetaceans, although technically whales, resemble porposes in both size and general appearance. They are born gray, but turn snow white at maturity. They are friendly and curious and allow people to swim among them, although harrassing these animals is illegal. These whales, known to be the most vocal, are also known as "sea canaries."
http://www.chem.ucla.edu/~alice/explorations/churchill/whale.htm