The Yukon is bordered on the north by the Beaufort Sea, part of the Arctic Ocean. The Beaufort Sea is generally calculated as covering 450,000 square kilometres and lying south and east of a line connecting Point Barrow, Alaska and Lands End, Prince Patrick Island in the Northwest Territory. The water of the Peel River and all other Yukon rivers that flow into the Mackenzie River discharges into the Beaufort at the vast Mackenzie Delta just east of the Yukon’s eastern border.
The Beaufort Sea is home to Herschel Island Territorial Park and also borders the shoreline of Ivvavik National Park. The coastline is low lying, with many barrier islands and sandpits. Scouring by ice and erosion by powerful storm surges contribute to this low profile. Inshore waters are shallow, with depths of only about 200 metres ranging out as far as 80 to 200 kilometres from shore. The width of this shallow shelf is greater in the Yukon and Mackenzie Delta region than in Alaskan waters. This is partly due to heavy discharges of sediment by the Mackenzie River. Beyond the coastal shelf, the water deepens rapidly to about 3,500 metres, reaching a maximum depth of nearly 4,000 metres in what is known as the Canada Basin.
Tidal fluctuations are minimal, ranging only from 0.3 to 0.5 metres in two daily fluctuations. Currents are also minimal and largely wind driven. The Beaufort Sea’s water is characteristic of the rest of the Arctic Ocean––low temperatures and low salinity. There is, however, a flow of Pacific water into the Beaufort Sea that brings with it salmon and herring. This contributes to the coastline’s popularity with seabirds, which use it as a vital summer breeding and migration staging area. Seals and whales, including the endangered bowhead whale, are also found here.
The Earth’s rotation causes an unusual phenomenon in the Beaufort known as the Beaufort Gyre. Water and ice in the Beaufort Sea circulate in a clockwise direction. As the water flows along the Yukon coast it encounters only one major obstacle––Herschel Island. This ocean current, through its effect on prehistoric glaciers and erosional forces, is responsible for the island’s separation from the mainland.