The third season of the Canadian science fiction–fantasy television series Sanctuary, premiered on Syfy in the United States on October 15, 2010 and consists of 20 episodes.

The Sanctuary team deal with the aftermath of the gigantic tidal wave released by Big Bertha while Will's life remains in balance but soon the errand comes to an end once Will leads one final plea to "Kali" A.K.A.

Following Will's return to life two abnormals appear to him to rekindle his memory and in doing so Will remembers an important message that Gregory sent for Helen to find an underground city with great technology and secrets.

Later Nikola sends an SOS call and after his rescue continues to help Helen in discovering the secrets of the city which eventually leads them to a Hollow Earth atlas.

The show returned to its original format, featuring a new short story for every episode until Tesla and Magnus discover a Praxian Stronghold.

"[22] Former Rome and Caprica actress Polly Walker will guest star as antagonist Ranna in two episodes during the middle of the season.

[23] In addition, former wrestler Edge (Adam Copeland) will guest star as an abnormal named Thelo in the season finale, scheduled to air during the Spring 2011.

Syfy later announced it would swap the show with Urban Legends where it was moved to Monday nights and be paired with Stargate Universe starting April 25 due to the low rating from the mid season premiere.