Sidney Island has an elevation of 77 metres (252 feet 8 inches) above mean sea level at its highest point.

It was formerly the Sidney Spit Marine Park under provincial jurisdiction.

There are 26 walk-in, backcountry camp sites available at Sidney Spit, and facilities include pit toilets and picnic tables.

Due to the high sodium content there is no longer any potable water at Sidney Spit.

Wildlife is abundant on Sidney Spit, as this island is an important resting spot for migrating shorebirds.