Smartfin, is a surfboard fin with sensors that measures multiple ocean parameters including salinity, pH, temperature, location, and wave characteristics. (surfrider.org)
«New satellite method enables undersea estimates from space: Statistical advance quantifies important ocean parameters in the illuminated ocean.» (sciencedaily.com)
You can't track that level of detail with litmus paper — pH is one of the hardest ocean parameters to measure. (newscientist.com)