Beneath Toronto’s bustling streets lies a hidden world most people never see — over 3,400 miles of tunnels, storm drains, and pumping stations that carry water where rivers once flowed. In this episode, we uncover how Toronto transformed its natural creeks and valleys into one of the largest underground sewer networks in North America.From lost waterways like Garrison and Taddle Creek to the engineering mega-projects that reshaped the city, this story reveals how politics, public health crises, and rapid growth buried Toronto’s rivers forever. What was once open water now flows in darkness — a hidden layer of the city’s forgotten history.