84%
Reef area under heat stress
The bleaching event that began in 2023 has exposed roughly 84% of the world's reef area to bleaching-level heat stress — the largest event ever recorded.
ICRI / NOAA Coral Reef Watch, 2025
An interactive story
Coral reefs support 25% of all marine life — and we're losing them. Scroll to see what's happening, and what's still possible.
Coral covers less than one percent of the ocean floor, yet about a quarter of all marine species pass through it — sheltering, spawning, hunting, hiding. Remove the structure and the city empties.
The colour you remember from photographs was never the coral itself. It came from algae living inside the polyps, trading sugar for shelter. When the water grows too warm, that trade collapses. The coral expels the algae and turns white — bleached, starving, still alive for a while.
What you're looking at is that moment, held still.
More than 90% of the excess heat trapped by greenhouse gases has gone into the sea. Reefs are where that number stops being abstract.
84%
The bleaching event that began in 2023 has exposed roughly 84% of the world's reef area to bleaching-level heat stress — the largest event ever recorded.
ICRI / NOAA Coral Reef Watch, 2025
14%
Between 2009 and 2018 the world lost about 14% of its living coral — roughly 11,700 km², more coral than covers all of Australia's reefs.
GCRMN Status of Coral Reefs of the World, 2020
70–90%
At 1.5°C of warming, 70–90% of tropical reefs are projected to decline. At 2°C, more than 99% are lost.
IPCC Special Report on Global Warming of 1.5°C
Coral can take its algae back if the water cools in time. Divers are already replanting nursery-grown fragments onto damaged reefs — and some of them are spawning again.
Nothing here moves on its own. Tap the node — the reef only changes if you choose to change it.
Restoration crews grow coral fragments on underwater trees, then attach them back onto bare reef rock. Fast-growing staghorn and elkhorn can be outplanted by the thousand, and some outplanted colonies have reached reproductive age and spawned in the wild.
Reefs have also rebounded on their own where heat stress eased — regional coral cover in parts of the world recovered measurably in the years after the 2016 bleaching event.
Planting coral does not cool the ocean. It buys time for the coral that can survive what we've already done — and keeps the genetic material alive until we stop the warming.
The reef you just restored took one click. The real one takes divers, nurseries, decades — and people who decide it's worth it. You can be part of that.