Milky seas effect

Milky seas, sometimes confused with mareel, are a luminous phenomenon in the ocean in which large areas of seawater (up to 100,000 km or 39,000 mi) appear to glow diffusely and continuously (in varying shades of blue). Such occurrences glow brightly enough at night to be visible from satellitesorbitingEarth. Unlike flashing waves or red-tide luminescence caused by algae such as dinoflagellates, milky seas originate from luminous bacteria.

Mariners and other seafarers have reported that the ocean often emits a visible glow which extends for miles at night. In 2005, scientists announced that for the first time, they had obtained photographic evidence of this glow. In a follow-up study, they observed a glow that persisted for over 40 days.