This is due to the presence of algae and plant life. Photosynthetic organisms contain chlorophyll, which not only appears green, but also absorbs red and blue light. Depending on the type of phytoplankton, the water may appear more blue-green to emerald green.

The vibrant green and turquoise colors of the Caribbean Sea are a result of the scattering and absorption of light, combined with the region's unique geography. The water is exceptionally clear because it is relatively "poor" in phytoplankton and suspended sediment, which usually give other oceans a darker or murkier blue-green look. When sunlight hits this clear, shallow water, it absorbs the red, orange, and yellow wavelengths of light more easily, while the shorter blue and green wavelengths are scattered back to our eyes. The presence of bright white sand—which is mostly composed of ground-up coral and shells—on the shallow seabed acts like a mirror, reflecting the light back up through the water and intensifying those bright turquoise and emerald tones. Additionally, the Mesoamerican Reef and other coral structures break up the waves and keep the water calm, preventing sediment from being churned up, which maintains the water's legendary cinematic clarity and allows the "tropical green" hues to shine through.