DemographicsCape Barren Island is approximately 580.41 square kilometres. In 2016 the population of Cape Barren Island was 66. The population is 47% male and 53% female. On average the monthly mortgage repayments in Cape Barren Island are $0 to $299. The most common weekly income bracket is $150 to $299 per week. Weekly rents in the area are on average $0 to $74.