Reducing CO2 emission has been a global consensus for mitigating climate change, which calls for offshore sequestration to store the CO2 captured from the atmosphere to undersea geological formations. However, offshore sequestration could cause environmental problems since CO2 leakage into the overlying seawater could cause seawater more acidic and giving rise to detrimental effects to the marine ecosystem. Therefore, autonomous CO2 leakage monitoring and detection technology becomes an emergent need in offshore CO2 sequestration practice. The research objectives include: a) Mapping CO2 distribution seawater using a school of robotic fish equipped with highly sensitive pH sensors; b) Scaling the monitoring range jointly leveraging the mobility of robotic fish, underwater wireless communications and navigation, and swarming control; c) Detecting exact leakage location on the seafloor will be identified using swarming of bio-inspired robotic fish.