The Seaway now permits ocean-going vessels to pass all the way to Lake Superior. Because of the virtually impassable Lachine Rapids , the Saint Lawrence was once continuously navigable only as far as Montreal. At that time, the land along the river was inhabited by the St. The Saint Lawrence River is in a seismically active zone where fault reactivation is believed to occur along late Proterozoic to early Paleozoic normal faults related to the opening of Iapetus Ocean. British troops were ferried via the Saint Lawrence to attack the city from the west, which they successfully did at the Battle of the Plains of Abraham. Initially, the whaling galleons from Labourd were not affected by the Spanish defeat.