Newfoundland

Newfoundlands''' are strong, massive dogs with webbed feet. They have a thick, water-resistant coat, making it the perfect swimming dog.

Origin
There are many theories as to who to Newfoundland was bred from. Many say it is a descendent of the Viking "Bear Dog" Others say it is a close relative of the Labrador Retriever, which is plausible due to the similar face, build and water swimming ability. Either way, the Newfoundland comes from Newfoundland, Canada. These muscular swimmers were used to haul boats to shore, drag lumber, pull mail sleds and deliver milk. They would also jump off boats to retrieve any items fallen overboard and to rescue drowning people. They are wonderful water rescue dogs and hard workers.

Temperament
The Newfoundland is the definition of a "gentle giant.They are very sweet, courageous, patient and intelligent. They are very obedient and mild with guests. They rarely bark, but are protective of their owners when they need to be. They are smart and quick and will know when there is danger and will hold intruders at bay. They are good with kids, cats, dogs and any other animal without evil intentions. They are messy when they drink and drool a lot, especially after a drink. They love to swim and will get to water every chance they get. They can be difficult to train.

Source
Dogbreedinfo.com