Scattered across a small number of coastal locations worldwide, certain bays exhibit a striking natural phenomenon: their waters glow with a faint blue-green light whenever disturbed by movement, whether from swimming fish, passing boats, or a hand trailed through the water at night. This glow is produced by dense concentrations of a particular type of microscopic marine organism called dinoflagellates, single-celled organisms capable of bioluminescence, the biochemical production of light through a chemical reaction occurring within their own cells. Scientists believe this light-producing capability likely evolved primarily as a defence mechanism; the sudden flash of light may startle potential predators or, alternatively, may serve to attract the attention of larger secondary predators that would, in turn, threaten the organisms initially attempting to feed on the dinoflagellates, a strategy sometimes described as a 'burglar alarm' effect. These bioluminescent bays require a highly specific and delicately balanced combination of environmental conditions to sustain the necessary dense concentrations of dinoflagellates, including calm, relatively enclosed waters, warm temperatures, and a reliable, consistent nutrient supply, conditions found in comparatively few locations around the world. Unfortunately, these same bioluminescent ecosystems have proven highly vulnerable to environmental disturbance; pollution, chemical runoff from nearby agricultural or urban development, and increased boat traffic have all been documented to significantly diminish or even entirely eliminate the bioluminescent effect in certain previously renowned locations. Conservationists in regions home to these rare bioluminescent bays have increasingly worked to establish protective regulations, aiming to preserve delicate ecosystems that offer both significant scientific research value and considerable ecotourism potential.