About 10 minutes after departing Naha Port on a clear day, the seascape below a boat reveals a vivid spread of soft corals and schools of tropical fish gliding through the water.
Before departure, the concentration of carbon dioxide in the water measured 407.3 parts per million, but at a site where soft corals carpet the seabed, the CO2 level dropped into the 360-ppm range.
Marine Tourism Development, an eco-tourism operator based in Naha, has launched a new kind of tour that measures underwater CO2 concentrations in real time while passengers observe the seafloor through a glass-bottomed boat.
AloJapan.com