The Blue Pond (Aoi Ike) in Biei, Hokkaido is breathtaking due to its cyan-blue hue. The water contains a natural mineral that reflects blue light.

Lake Mashu in Hokkaido is reportedly the world’s clearest caldera lake. Since it has neither inlets nor outlets, silt, algae, and other forms of suspended matter do not cloud the water. This enables the waters to compromise almost rainwater entirely, so the lake is so blue that it is termed “Mashu blue”.

The blue-footed booby’s courtship display includes spreading its wings and showing off its bright blue webbed feet to impress the female.

You may be surprised to know that prawns have blue blood because they have a pigment called hemocyanin. This copper-based protein gives blue colour to the blood.

Blue penguins moult to replace their own and worn feathers. It takes about 2 to 3 weeks for each moulding session to complete its course.

The melanin found in a bluebird would make it look almost black, but tiny air sacs in its feathers scatter light and make it appear blue.

When threatened by potential attackers, the skin cells of the golf-ball sized blue-ringed octopus quickly display bright blue rings to warn them off. This is known as warning colouration.

Sometimes when people are very cold, their lips and fingers can appear blue. But the blue soon disappears when the person warms up again. Their skin colour returns to a normal pinky colour.

The peacock butterfly's blue eye-like spots fool a predator into thinking it is attacking a much larger animal.

Stars emit colours of many different wavelengths according to their temperatures. The hotter the star, the more blue it emits whereas the cooler the star, the more red it emits.

Chlorophyll absorbs blue and red light from the Sun as the frequencies of these lights are the closest to that of chlorophyll. Although chlorophyll absorbs blue and red light, it reflects the green light when illuminated by white light. That’s the reason we see the lawn as being green.