Even with stakes as high as these, the decision to apply antibiotics is still risky. Widespread use in agriculture and medicine has already led to a rise in drug-resistant bacteria. To minimize the danger, Neely and her colleagues mix amoxicillin, a common, broad-spectrum antiseptic that killed the disease in lab trials, into a paste that slowly releases the drug into the coral’s tissues. The concoction hardens when exposed to seawater, making its contents less likely to seep into the ocean. As Neely and I saw firsthand, however, these targeted doses might fall short. Despite the millions of dollars marshalled in ongoing efforts to fight this outbreak, there aren’t enough bodies in the water to treat every diseased coral on every ailing reef before SCTLD obliterates them. Instead, researchers and managers are focusing on a handful of key spots where endangered species could vanish. There is no guarantee they can defeat such an aggressive pathogen, but they’ll fend it off as long as possible.