The anchor chain of Argo drops to the seafloor. We’re in the middle of nowhere. Boarding the dingy, we head toward the shallow reef. I flip backward into the 29°C water, surrounded by crystal-clear visibility and vibrant coral. It’s our first dive on the Great Barrier Reef with Citizens of the Reef, and I’m about to free dive Briggs Reef.

As I descend, a field of purple branch coral comes into view, home to tiny aqua blue fish. Yellow fish dart past redirecting my gaze, as a school of microscopic green chromis fish swirl around me like a cloud. It's been too long, and I’d forgotten how surreal and impossible this 500,000-year-old ecosystem is. The fish weave through the coral, some bold, others cautious. I wish I could stay, but I must resurface for air. Floating above the surface, I reflect on the wonder of this place and why I’m here—to participate in the Great Reef Census.