A few larger ones lie west of the Mackenzie River , such as Herschel Island ( 4 km ( 2.5 mi ) off the shore , area 18 km2 ( 6.9 sq mi ) ) and Barter Island ( 0.3 km ( 0.19 mi ) from the coast , area 13 km2 ( 5.0 sq mi ) ) .
A few larger ones are west of the Mackenzie River , such as Herschel Island ( 4 km ( 2.5 mi ) off the shore , and Barter Island ( 0.3 km ( 0.19 mi ) from the coast .