77-year-old scientist Charlie Veron has spent his much of his career underwater charting the world's coral reef wonderlands. Now, as the Great Barrier Reef faces its biggest challenge, he reveals an ambitious rescue plan for the future. He is collecting the 400 species of coral on the Great Barrier Reef to preserve in a "coral ark" or biobank. It’s a bold plan, but could it be the solution to future-proofing our precious world heritage-listed site?