Tanquary Fiord

Tanquary Fiord is a fjord located on the north coast of Ellesmere Island in Nunavut, Canada, within Quttinirpaaq National Park. It extends 48 km (30 mi) in a northwest direction from Greely Fiord. Radiocarbon dating indicates deglaciation occurred between 10,000 and 4,100 BP, followed by glacial readvance and ice shelf formation until 2,400 BP. A period of glacial retreat ensued until 1,400 BP, after which glacial readvance and nearby ice rises have been observed.

The fiord's head is where four river valleys converge, with three ending in floodplains and one in a river delta. Carbon dating suggests the fjord was free of glacial ice around 6,500 years ago. In recent decades, side glaciers have receded significantly. Despite its high latitude, Tanquary Fiord experiences 65 frost-free days annually, with summer temperatures reaching up to 18 °C (64 °F).

Human activity in the area includes the Defence Research Board's "Operation Tanquary" from 1963 to 1972, focusing on oceanography. The remote location limits habitation, though a Parks Canada Warden Station operates during summer, and nearby Tanquary Fiord Airport provides access via charter aircraft or icebreaker cruise ships. A meteorological station was established at Eureka in 1947, approximately 175 km (109 mi) southwest of the fiord. The fiord is named after Maurice Cole Tanquary, a friend and fellow explorer of Donald Baxter MacMillan.