(bright music) (bugs chirping) (waves crashing) (water sloshing) - [Narrator] Across all of planet Earth, (water rushing) nature's diversity dances in synchrony.

But in the western hemisphere, there exists an ecosystem unlike any other.

(bright music intensifies) From the heart of its desert, to its towering mountains, across vast grassland, (grass rustling) and precious chaparral.

(birds calling) (grass rustling) San Diego is the most biodiverse county in America, but this rare mosaic of life that we hold so precious may not last forever.

(fire hissing) (dramatic music) (bright music) Amidst escalating pressures, these once thriving ecosystems are vanishing at an unprecedented rate.

(ethereal music) How do we teach the next generation about the land we live in now, what it once was, and what it will be in the future?

(water hissing) (expansive music) (water burbling) Follow one family on their quest to discover this national treasure.

(expansive music intensifies) Looking to experts for a plan and adventures for understanding.

(expansive music continues) (air whooshing) Discover San Diego as "The Most Biodiverse Place in America."

(leaves rustling) (birds calling) (gentle music)