Seal Island is an island on the outermost extreme of Southwestern Nova Scotia, Canada. It is in the Municipality of the District of Argyle in the Yarmouth County. It is approximately 4.3 kilometres long and 0.8 kilometres wide and is surrounded on its east, south and west sides by dangerous shoals. It is surrounded by the Atlantic Ocean and is the b…Seal Island is an island on the outermost extreme of Southwestern Nova Scotia, Canada. It is in the Municipality of the District of Argyle in the Yarmouth County. It is approximately 4.3 kilometres long and 0.8 kilometres wide and is surrounded on its east, south and west sides by dangerous shoals. It is surrounded by the Atlantic Ocean and is the biggest of a group of five islands which extend north for 12 kilometres. It is the second southernmost point of land of Nova Scotia. The southern tip of nearby Cape Sable Island is 250 metres farther south than the southern tip of land on Seal Island.