Blue carbon is the carbon stored in coastal and marine ecosystems if they remain undisturbed.

Coastal ecosystems such as mangroves, tidal marshes and seagrass meadows sequester and store more carbon per unit area than terrestrial forests, and are now being recognized for their role in mitigating climate change.

pathways:

02.06.2022 / PNAS / Climate benefits from establishing marine protected areas targeted at blue carbon solutions

05.04.2022 / EDF / Blue carbon: A better tomorrow begins below

Wikipedia / Blue Carbon