Waukegan () is the largest city in and the county seat of Lake County, Illinois, United States. Situated approximately 35 miles (56 km) north of Downtown Chicago and 21 miles (34 km) northeast of O'Hare International Airport, it is an industrial suburb of Chicago and a principal city within the Chicago metropolitan area. As of the 2010 census, the population of Waukegan was 89,078 (estimated to have decreased to 86,075 in 2019), making it the tenth most populous city in Illinois. Waukegan is a predominantly working-class community, with a sizeable middle-class population.

Ironsand, also known as iron-sand or satetsu(in japanese), is a type of sand with heavy concentrations of iron. It is typically dark grey or blackish in colour. It is composed mainly of magnetite, Fe3O4, and also contains small amounts of titanium, silica, manganese, calcium and vanadium. Ironsand has a tendency to heat up in direct sunlight, causing temperatures high enough to cause minor burns. As such it forms a hazard in New Zealand at popular west-coast surf beaches such as Piha.