During the quest for the Northwest Passage it was entered several times until it was realized that Prince Regent Inlet-Gulf of Boothia is a cul-de-sac for practical purposes. In 1819 William Edward Parry penetrated more than 100 miles south before turning back. In 1829 John Ross (Arctic explorer) passed through it and was frozen in in the Gulf of Boothia for four years before escaping. In 1852 Bellot Strait, the frozen western exit, was discovered. In 1858 Francis Leopold McClintock tried to pass this strait, gave up, and wintered near its mouth.