Great Barrier Reef Region Guide

Colours of the Reef

Reef corals are a riot of colour, but only a few metres down they appear to be mainly blue and green.

The reason is that seawater absorbs colours at both ends of the spectrum, cutting out 40-50% of red and 30-40% of orange in the first metre.

The effect increases with depth until only blue and green are left.

When artificial light, such as a powerful underwater torch, is introduced the missing colours can be seen again.