When we think of rivers, we often picture what floats on the surface. But beneath the current lies an entirely different world. In Nathalie Lasselin’s Deep Dive, we take you below the surface of the St. Lawrence River, revealing an ecosystem as wild as any rainforest.

Above the water, bald eagles and ospreys circle the skies while beavers and muskrats patrol the banks. Below, diver Nathalie Lasselin leads us into a freshwater realm alive with smallmouth bass, gobies, and rocky reefs that shelter countless species. This is not just a river, it’s a hidden planet.

Lasselin, who has explored Arctic waters and Chinese cave systems, comes home to Montreal to spotlight the challenges facing her own backyard river. Her dives aren’t just about discovery, they’re about impact. Alongside her team, she collects water samples and hauls up debris. In a single year, they removed over six tons of waste, the weight of an African Bush Elephant, from the St. Lawrence.

Through breathtaking visuals and raw determination, Nathalie Lasselin’s Deep Dive forces us to reconsider what rivers hold and what we stand to lose if we fail to act. Protecting rivers isn’t abstract, it’s hands-on, underwater, and urgent.