Sidney Island, known to aboriginal people as Sallas Island, was one of the earliest places settled on Canada’s Pacific Coast. It was on the route from Fort Victoria to the Fraser River gold rush in 1858. The following year the Hudson Bay Company began offering land for sale, and to make it appear more civilized, changed its name to Sidney Island. For some years following the turn of the century, a brickworks operated in the area now within the marine park, utilizing the island’s fine clay.

Some of the huge old growth Douglas Fir timber was logged during the two World Wars, and in its place vigorous stands of second growth have flourished.

In 1910, a group of Victoria businessmen purchased Sidney Island as a hunting preserve, though vegetable farming and sheep raising continued for some decades. In 1981, after the marine park was created, the remainder of the island was purchased by Sallas Forest Limited Partnership. Today, following official approval of a development plan to integrate low-density residential development with forest management and protection of areas of special environmental significance, ownership is being transferred to strata owners organized under a strata corporation.