Combined with the text, in my own words: "Why is the sea blue?"

In fact, this is the magic of the sun. As we all know, sunlight consists of seven colors: red, orange, yellow, green, cyan, blue and purple. When the sun shines on the sea, red light and orange light with longer wavelength can overcome obstacles and go forward bravely because of their greatest transmittance. In the process of progress, they are constantly absorbed by seawater and marine life. Blue light, purple light, etc. Because of their short wavelength, when they encounter obstacles from seawater, they will scatter in all directions or even reflect back, and only a few of them will be absorbed by seawater and marine surface organisms.

The sea looks blue because this scattered and reflected blue and purple light enters our eyes. The deeper the sea water is, the more blue light is scattered and reflected, and the bluer it looks.