Hospital (Hardwood) Island which was a quarantine station for inbound immigrants who were diagnosed as having cholera. It is thought that there were as many as 400 Irish immigrants - many of them children - buried there. My Mom told of how half of her Mother's family died in the Thousand Islands of cholera, and other diseases, while they were awaiting admittance to the United States. Half of the survivors turned back and became Canadian citizens, just to get out of the camps and have a better chance of surviving.
Quoted here by Eric Thornton