East of this point the three diverge into the Frontenac Arch. It meets Highway137 at an interchange at the parkways midpoint; the Ontario approach to the Thousand Islands Bridge which continues as Interstate 81 south of the Canada–United States border. The parkway continues northeast, serving the riverside communities of Darlingside, Rockport, Narrows, La Rue Mills and Mallorytown Landing. At Butternut Bay, the Thousand Islands Parkway merges into the eastbound lanes of Highway401 and a left-hand exit provides access to the parkway from westbound Highway401.