Bras d'Or Lake Biosphere Reserve

Bras d'Or Lake Biosphere Reserve (established 2011) is a UNESCO Biosphere Reserve located at Bras d'Or Lake, Cape Breton Island, Nova Scotia, Canada. It consists of a salt-water estuary watershed inland sea with three passages to the Atlantic Ocean. The Holocene transgression flooded a complex river-lake system of diverse geology, creating the small, deep inland sea with 12 significant watersheds draining both highlands and lowlands.

The terrestrial, marine and coastal habitats provide a home for human populations, as well as other organisms. The original settlers colonized the region following the retreat of glaciers, and today their descendants make up the five Mi'kmaq populations that account for a significant proportion of the population occupying large areas of the watershed.