Shelley Island is an island located off the coast of National City.
Shelley Island was converted into an interplanetary port of entry by President Olivia Marsdin for alien immigrants until her resignation. Afterwards, the Children of Liberty converted the island into a base until Supergirl foiled their plan.
Shelley Island has a large monument of a hand holding a torch. Power-dampening pylons located around the island's perimeter that negate alien powers.
In late 2018, Shelley Island was shut down and abandoned following Marsdin's resignation. Shortly after, the Children of Liberty converted the island into their base of operations.
After capturing both Supergirl and James Olsen, the Children of Liberty intended to force James to make a propaganda video where he detonates a bomb that destroys the Shelley Island monument, while not knowing Supergirl was trapped inside. However, thanks to the intervention of Manchester Black, Supergirl threw the bomb away from the island and her and James were able to escape.