Filmed by camper Larry Griffith, the YouTube video shows the bear galloping through the water and charging at the camp site.
According to the Guardian, the bear circled the campers three times and later lost interest as it was only a bluff charge.
Deemed a threatened species, only about 1,000 grizzlies remain in the continental U.S., where they are protected by law. But many grizzlies still roam in Canada and Alaska, where hunters nevertheless pursue them as big game trophies, according to National Geographic.
This isn't the first time an altercation between tourists and a wild animal has been caught on film.
Two years ago, footage emerged of a lion sneaking up and attacking a tourist who was on safari.
Meanwhile, in 2009 a bear went after tourists in Japan at a highway rest stop and was later shot in a souvenir shop.