condition. why scientists think more must be done to explore the world s oceans. reporter: here off the coast of tahiti, a stunning discovery. up to 230 feet below the surface was this, a huge, untouched, rose-shape coral reef nearly two miles long. researchers on a united nations-led discovery mission discovered it liveing near the twilight zone depth of the ocean. 100 to 200 feet below the ocean where there is just enough light to sustain life. they found one of the largest coral reefs, appearing unaffected by climate change, stunning since warming waters have wiped out nearly half of the earth s known reefs. over the next couple of decades, there will be a 90% decline according to latest projection himself. it shows us still how uphill we know about our own planet and