Most of the rivers have a tidal bore, a wave front of the incoming tide that "bores" its way up a river against its normal flow. Notable ones include those on the Petticodiac, Maccan, St. Croix, and Kennetcook rivers. Before the construction of a causeway in 1968 and subsequent siltation of the river, the Petitcodiac River had one of the world's largest tidal bores, up to high. Since the opening of the causeway gates in 2010, the bore has been coming back, and in 2013 surfers rode it a record-breaking .