Alaska State Troopers say the two were in an inflatable kayak Sunday that flipped on the Placer River about 2.6 miles upstream from the Seward Highway Bridge.
The two were wearing life jackets and swam to shore but lost their boat and gear.
Family members in another boat stopped but the two were wet and hypothermic until another set of rafters came upon them and helped make a fire.
They activated the satellite beacon at about 7 p.m.
The International Emergency Response Coordination Center gave global positioning system coordinates to troopers.
A Girdwood trooper and a U.S. Forest Service officer used a jet boat to reach the stranded boaters.
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