The oceans, the vast expanses of water that cover our planet, have never ceased to fascinate mankind. Among the most intriguing phenomena are the luminescent seas, those sea areas that mysteriously light up at night. For centuries, they have fueled legend and speculation, captivating sailors and scientists alike.
In 2025, a major scientific breakthrough has finally lifted the veil on this bewitching phenomenon. What recent discoveries explain this marine bioluminescence? Dive into this article to discover how science has unlocked one of the best-kept secrets of the ocean depths.
Milky seas phenomenon
Milky seas, a rare oceanic phenomenon, are distinguished by their uniform white or pale green glow, intense enough to be visible from space. Unlike the blue sparkles of bioluminescent plankton, these vast expanses of light can cover more than 100,000 km² and persist for several weeks.
Almost 60% of the 240 events recorded are concentrated in an area between Somalia, Socotra Island in Yemen and the Maldives. This phenomenon is often linked to major climatic oscillations such as the Indian Ocean Dipole and the El Niño Southern Oscillation, which favor the appearance of these glows by bringing in warm, nutrient-rich surface waters.
Integrating historical evidence and modern technology
Researchers at Colorado State University and NOAA’s Cooperative Institute for Atmospheric Research have created a comprehensive database of milky seas, combining 240 credible accounts from sailors since the 17th century with modern low-light satellite imagery.
This innovative approach makes it possible to predict more precisely where and when these phenomena might occur. However, studying such a rare phenomenon remains complex. Scientists must overcome the challenge of collecting biological and chemical samples in real time, as only one expedition in 1985 succeeded in collecting direct data from an active milky sea.
Ecological and economic implications
Milky seas may play a little-known role in the global carbon cycle, by transferring organic matter from surface blooms to deep waters. This process, while potentially beneficial for the ecosystem, could also signal environmental stress. Vibrio bacteria, suspected of being at the origin of these phenomena, can harm fish and shrimp, threatening local fisheries.
Understanding these events is crucial to assessing their impact on marine biodiversity and regional economies. Future research should focus on targeted expeditions to collect essential data, in order to better understand and manage these potential impacts.
