The salmon that fill the rivers of the Pacific coast of North America have one of the most miraculous and mysterious life-cycles in the entire animal kingdom.

After years feeding in the Pacific Ocean, they travel thousands of miles back to the rivers of their birth to spawn and to die. Using miniature underwater cameras, 'The Silver Tide' reveals the drama and danger of the salmon on their last great journey, as they encounter and overcome fishing nets, hungry bears, raging floods and massive waterfalls. Each year, despite these obstacles, millions of fish reach their final destination, and in doing so, sustain one of the most beautiful and wild landscapes on Earth.