Walk to the end of Main Street and follow the path down to the riverbank where the Susitna, Chulitna, and Talkeetna rivers converge. The water is the grey-green of glacial melt, fast and cold even in summer. On a clear day -- which is far from guaranteed -- Denali rises impossibly large to the north, filling the sky beyond the treeline.
This is the best free view in town. Bring binoculars and you may spot eagles working the river. Salmon runs bring bears to the banks in season, though they are more common on the smaller tributaries upstream. The confluence is a short walk from the town center; just head north from Nagley's Store.