Milky seas effect

Milky seas, or mareel, is a condition on the ocean where large areas of seawater (up to 6,000 sq mi or 16,000 km) appear to glow brilliantly enough at night to be seen by satellites orbiting Earth. Modern science only tentatively attributes this effect to bioluminescent bacteria or dinoflagellates, causing the ocean to uniformly glow an eerie blue at night. However, there is no modern research to prove that bioluminescent bacteria are capable of illuminating the ocean from horizon-to-horizon and for days at a time, as described in mariner's tales for centuries (notably appearing in chapter 23 of Jules Verne's Twenty Thousand Leagues Under the Sea); and, in fact, the effect has not been rigorously documented nor thoroughly explained, even in modern times.