Watch TV Series The Swarm Online Free. The global environmental thriller is set in the present day, where anomalies and unnatural behavior in marine animals are causing upheaval all over the world. The Swarm follows a global group of scientists who come together to tackle one of the biggest challenges mankind has ever faced. They make the chilling discovery that deep at the bottom of the sea resides a collective intelligence which has suffered the ravages of civilization on its habitat – and decided to fight back.