Boularderie Island (pronounced "bull-la-dree") is an island separating the Cabot Strait from Bras d'Or Lake on the eastern coast of Cape Breton Island, Nova Scotia, Canada. It takes its name from Louis-Simon le Poupet de la Boularderie, who was granted the area as a concession from the King of France.
At 40 km (25 mi) long and between 3 km (2 mi) to 10 km (6 mi) wide, Boularderie Island is Nova Scotia's second largest island after Cape Breton Island.
Two outlets of Bras d'Or Lake run on each side of the island to the Atlantic Ocean:
The extreme northeastern end of the island at Point Aconi fronts the Cabot Strait, whereas the extreme southwestern end at Kempt Head fronts the northern basin of Bras d'Or Lake.
The majority of the island is heavily forested, however it is encircled by roads. The Trans-Canada Highway (Highway 105) traverses the island diagonally from Bras d'Or in the east to Big Bank in the west. The island hosts a number of farms along its southern and eastern shores.
The island is divided across two of the province's counties with the north and western side being part of Victoria County (approximately 2/3 of the island's land mass), and the remainder of the southeastern end being part of Cape Breton County.
The northern end of the island in the community of Point Aconi has been home to several underground coal mines with the last one closing in November 2001. There has also been several controversial proposals to strip mine near-surface deposits which is meeting significant opposition from residents in the northern end of Boularderie Island. The Point Aconi Generating Station and the Eyking Family Farm are located in the Boularderie community as well.