In 1832, a group of British soldiers returned to Québec City from a stint in India and unknowingly introduced the populace to cholera - around 3500 people (or 10% of the population) subsequently died. To prevent such scourges, the local authorities set up a quarantine station on Grosse Île, a small island in the St Lawrence River to the city's east. The station handled mainly European immigrants, processing over four million people before its closure in 1937. One of its busiest periods was during the 1840s, when the Irish potato famine drove 100,000 people to Canada, 7500 of whom died on Grosse Île of typhus.
Since 1994 it's been possible to take guided tours of Grosse Île to inspect the old disinfection chambers, hospital, cemetery and immigrants' living quarters. The tours are conducted from a marina in the village of Berthier sur Mer, which is located on the southern bank of the St Lawrence roughly 60km (37mi) from Québec City. Grosse Île floats just off the north-eastern corner of the much larger Île d'Orléans, a highly popular holiday destination due to its centuries-old cottages and manors, abundant galleries of island art, and lovely river-enhanced scenery.