euphotic zone The surface waters of the sea or of a lake where enough light penetrates for photosynthesis to occur, down to about 80 metres.

• 透光区海洋或湖的表面水域或有充足的光深入，有光合作用的区域，向下至大约八十公尺。区域的深度随著水的灭绝系数，日光投射角，白昼与夜晚的长度而改变。