- marine organic geochemistry
- marine pharmacognosy
- marine photochemistry
- marine physical chemistry
- marine physics
- marine policy
- marine pollutants
- marine pollution
- marine pressure hydrophone
- marine reflection seismic survey
- marine refraction seismic survey
- marine resource chemistry
- marine resources
- marine salvage
- marine sciences, ocean sciences
- marine sedimentology
- marine seismic profiler
- marine seismic streamer
- marine seismic survey
- marine seismograph
- marine stratigraphy
- marine technology
- marine towage
- marine wide-angle reflection seismic survey
- maritime air mass
- marking
- marsh organism
- mass balance
- mass budget
- mass transfer
- mean sea level, MSL
- mechanical bathythermograph, MBT
- medical security for diving
- megafauna
- megalopa larva
- megaplankton
- meiobenthos
- meiofauna
- meroplankton, transitory plankton
- mesocosm
- mesopelagic fish
- mesopelagic organism
- mesopelagic zone
- mesoplankton
- mesopsammon
- mesoscale eddy
- meteorological tide
- microbenthos
- microbivore
- microcolony