‘Blue carbon’ refers to the carbon stored in marine and coastal ecosystems, namely mangroves, seagrass and saltmarsh. We currently work with three certified mangrove projects, and are also developing a new blue carbon methodology focusing initially on the quantification of carbon in mangrove forests. The methodology will also include seagrass ecosystems as development continues. Other blue carbon ecosystems (e.g. kelp or other macroalgae) are not currently eligible.