For nearly two decades, Indonesian marine scientist Syafyudin Yusuf has worked with former poachers to rehabilitate coral reefs destroyed by their use of dynamite for fishing. They have restored to health 11.5 hectares (roughly 30 acres) of corals around a group of 120 islands known as the Spermonde archipelago in the Makassar Strait off Sulawesi. Fifteen years ago, only 2% of the area's original reef area remained undamaged, according to research by Makassar's Hasanuddin University, as fisherfolk used explosives and chemicals, which have now been banned.