海
 |
海又被称为“大海”，是指与“大洋”相连接的大面积咸水区域，通常大型内陆盐湖、没有与海洋连通的大型咸水湖泊如里海、加利利海是“海”。海分为边缘海、内陆海和地中海。
海在大洋的边缘，是大洋的附属部分。海的面积约占海洋的11%，海的水深比较浅，平均深度从几米到3000米。由于海靠近大陆，受大陆、河流、气候和季节的影响，水的温度、盐度、颜色和透明度都受陆地影响出现明显的变化，有的海域海水冬季还会结冰，河流入海口附近海水盐度会变淡、透明度差。和大洋相比，海没有自己独立的潮汐与海流。
List of seas, divided by ocean
- Bering Sea
- Gulf of Alaska
- Sea of Cortez (aka Gulf of California)
- Sea of Okhotsk
- Sea of Japan
- Seto Inland Sea
- East China Sea
- South China Sea
- Sulu Sea
- Celebes Sea
- Bohol Sea (aka Mindanao Sea)
- Philippine Sea
- Flores Sea
- Banda Sea
- Arafura Sea
- Timor Sea
- Tasman Sea
- Yellow Sea
- Coral Sea
- Hudson Bay
- Baffin Bay
- Gulf of St. Lawrence
- Caribbean Sea
- Gulf of Mexico
- Sargasso Sea
- North Sea
- Baltic Sea
- Irish Sea
- Mediterranean Sea
- Bay of Biscay
- Gulf of Guinea
Landlocked seas
Extraterrestrial seas
Lunar maria are vast basaltic plains on the Moon that were thought to be bodies of water by early astronomers, who referred to them as "seas."
Liquid water is thought to be present under the surface of several moons, most notably Europa.
Liquid hydrocarbons are thought to be present on the surface of Titan, though it may be more accurate to describe them as "lakes" rather than "seas". The distribution of these liquid regions will hopefully be better known after the arrival of the Cassini probe.
Science
The term "sea" has also been used in quantum physics. Dirac sea is an interpretation of the negative energy states that comprises the vacuum.