Yukon shall be bounded as follows: On the south, by the Province of British Columbia and the State of Alaska; on the west, by the said State of Alaska; on the north, by that part of the Arctic Ocean called Beaufort Sea; and on the east, by a line beginning at the intersection of the north boundary of British Columbia with a line passing through a boundary pipe post set in concrete, trench and mound, numbered 600, planted by the British Columbia-Yukon-Northwest Territories Boundary Commission approximately 1 chain westerly of the left bank of the Liard River, said line having a bearing of 309 degrees with reference to the meridian through said post; thence northwesterly along said line to a point on the line of watershed separating the streams flowing into the Liard River below the La Biche River or into the Mackenzie River from those flowing into the La Biche River, into the Liard River above the La Biche River, or into the Yukon River; thence northwesterly along said line of watershed to the line of watershed of the basin of Peel River; thence northerly along the line of watershed between the Peel and Mackenzie Rivers to the sixty-seventh degree of north latitude; thence westerly along the parallel of the sixty-seventh degree of north latitude to the line of watershed between the Peel and Yukon Rivers; thence northerly along the said line of watershed to the trail across the portage in McDougall Pass between Rat and Bell Rivers; thence due north to the northern limit of the Yukon territory; the said territory to include the islands within twenty statute miles from the shores of the Beaufort Sea as far as the aforesaid due north line from McDougall Pass.