Sirmilik National Park (; Inuktitut: "the place of glaciers") is a national park located in Qikiqtaaluk, Nunavut, Canada, established in 1999. Situated within the Arctic Cordillera, the park is composed of three areas: most of Bylot Island with the exception for a few areas that are Inuit-owned lands, Kangiqłuruluk, and Baffin Island's Borden Peninsula. Much of the park is bordered by water.
Geographically, it is representative of the Northern Eastern Arctic Lowlands Natural Region as well as parts of the Lancaster Sound Marine Region. They named several features of the area including Lancaster Sound and Bylot Island in 1616. It was 200 years before the next official attempt to find the Passage through this area. The expedition by the British explorer John Ross in 1818 confirmed the accuracy of Baffin's charts, but ended when he saw what he believed were mountains blocking the end of Lancaster Sound. The northern area, including the Hartz Mountains, are composed of flat, dissected rock rising to over above sea level. Admiralty Inlet forms a western border, with Elwin Inlet also to the west, while Navy Board Inlet forms a border to the east, separating the peninsula from Bylot Island. Navy Board Inlet's coastal cliffs rise to . and has been extensively modified by glacial erosion. Extensive glaciers dot the island including the Kaparoqtalik Glacier. Vertical cliffs along the coastline are made up of Precambrian dolomite. The island's north shore faces Lancaster Sound, a polar bear maternity den area, also noted for its high concentrations of marine wildlife. To the northeast of the park is Baffin Bay and to the south lies Pond Inlet and Eclipse Sound.
In the north of Baffin Island, there is a polar maritime climate which means long, cold winters and short, cool summers. The spring does not end until mid-June and the warmest period is late July and early August, with average maximum temperatures of 10 °C. The coldest month is January as the average maximum temperatures of about −30 °C. Rainfall is relatively abundant, contributing to the flora seen in the park.
Fauna and flora
thumb|upright|Kittiwakes on the cliffs of Cape Graham Moore
thumb|[[Bowhead whale tail-slaps in a distance]]
;Fauna
Beluga whales, Arctic foxes, seals, Arctic hares, walruses, and caribou are found in this park. Sirmilik is one of eight Canadian national parks that contains polar bears. Arctic wolves roam and inhabit this park.
A major seabird colony is located in the area of Baillarge Bay. Seabird colonies are also located on Bylot Island which have a large colony and nesting area of greater snow geese. In 1965, Bylot Island enclosed within the park was also declared as a "Migratory Bird Sanctuary" in view of the large number of migratory birds in the area. A record 100,000 birds are reported to pass the park during summer months every year, and the large geese population of the island is known to constitute the most abundant herbivores of the island.
;Flora
The wetlands of the park (10% of the area) have abundant vegetation of water sedge (Carex aquatilis), white cottongrass (Eriophorum scheuchzeri) and tall cottongrass (Eriophorum angustifolium). Other types of grass include the Fisher’s tundragrass (Dupontia fisheri), the polar grass (Arctagrostis latifolia) and semaphore grass (Pleuropogon sabinei). In addition, several species of brown moss have been recorded. In the Arctic environment of the southern part of the island 360 species of plants have been documented, which are considered to have rare quality and productivity.