They are giants—stretching more than 300 feet above the ground, with hidden gardens and mysterious predators thriving within their canopy. National Geographic reveals the unexplored environment of redwoods using high-tech aerial laser surveys and breathtaking imagery. Obsessive redwood climber Steve Sillett of Humboldt State University investigates their monster crowns, tallying biological material and discovering new record-breaking trees, while escaping falling branches and crashing trees in the process. Down below, National Geographic Explorer-in-Residence Mike Fay charts the redwood range. It is an epic yearlong exploration to size up the past and future of this primeval tree threatened in 21st century California.

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Documentary