With China already having three maritime satellites in orbit, John Walker of the Nottingham Trent University said adding eight more was "a very significant investment just to monitor water."
"I would expect the real value of these satellites to be more military and intelligence gathering," he said.
Walker has previously worked in scientific research within Britain's Ministry of Defense, the BBC reported.
China's State Oceanic Administration said the present marine monitoring satellites oversee around 115,000 square miles of ocean around the country.
Four of the new satellites will observe the color of ocean waters while two will study currents and two will be equipped with radar, National Satellite Ocean Application Service Director Jiang Xingwei told the China Daily newspaper.