Technical term used in oceanography, climatology, and geography. Synonymous with 海面 (かいめん) but more formal and often used in compound terms like 海水準変動 (sea-level change).
See also: 海面
Sea levels are rising due to global warming.
Research on sea-level changes in this region is being conducted.
Compound of 海水 (かいすい, 'seawater') and 準 (じゅん, 'level, standard'). The term is a modern scientific coinage.