Children's Island, formerly known as "Cat Island" is an island off Marblehead, Massachusetts, and is part of the City of Salem, Massachusetts. The YMCA of the North Shore has owned and operated a children's day camp on it since 1955. The first written record of the island was in 1655 when it was granted to Governor John Endecott. It was then bought and sold several times until around the Revolutionary War when the Essex hospital was built as a smallpox inoculation site. The hospital was burned down by townspeople of Marblehead. By the end of the 19th century, the Lowell island house was established as a summer resort. This was run for about 30 years before being converted into a sanitarium for sick and crippled children until 1946. The island then lay unused until bought by the YMCA and co