Milky Sea article – published in "Flying Fish", Ocean Cruising Club Journal (June 2015)

Seeing a display of nature for the time can often be unforgettable experience. However, seeing a phenomenon when you have no idea what you are witnessing is unnerving. Describing it, having no parallels, is confounding. A few days into our Indian Ocean crossing, we saw something extraordinary with 3 nights remaining.

The passage had been terrific. We were making up for a late start from Opua in early July, and intended to cross the Indian Ocean before the cyclone season. We sailed to Vanuatu - first Tanna and then on to Port Vila. Leaving Vila on 21st July, we left our destination open, waiting to see what the conditions would bring. The first few days were fairly bumpy, winds on the beam in the 25kt range with awkward swell.  We arrived at the Torres Strait at the Pandora Passage (named after the ship sent to recover the Bounty mutineers, which foundered in the straits) mid-morning on Aug 1st. The 8 hours until dusk were quite easy, as winds were light and we were sailing "fast and free". At sunset we began the SSW leg through the "Deep Water Passage” of the Torres Straits, which brought us close hauled for the next 100nm or so. The channel is well marked, and with calm seas, sailing was fast. Shortly after daybreak, we could see the large ship wrecked on Bet Reef - ironically providing great assistance to other navigators. As we passed Kircaldie reef and the wind freed-off, Henri baked a pizza and we put on some music in the cockpit. With lots of islands, reefs and even the Australian mainland in sight, we felt like we were day-sailing through the green water (10m-20m deep) of the straits. We shot through the Prince of Wales channel, and a fantastic sunset welcomed us to the Gulf of Carpentaria.

We had blustery, squally conditions in the Gulf, but fortunately we had wind aft of the beam and swells were generally not large. Speeds were good. One surprising thing about the gulf is how green the water is - even when rough - it is a turquoise colour and was a great contrast with the deep ocean blue of the Pacific. By August 6th, we were 40nm E of the longitude of Darwin, where we might have stopped, but having no need of a break, or diesel, water or other supplies we pressed on. About 500nm west of Darwin, lies the uninhabited Ashmore Reef, which we considered stopping to break the passage. In the event, we decided that what we needed was an inhabited island where we could go ashore and stretch our legs - and that meant Christmas Island, 1000nm to the W of Ashmore Reef.

Sailing was fast, pleasant and, pulled by our twin head-sails,  the miles were rolling by. During this week we recorded a noon-noon run of 182nm (over the ground) - a record for Pamina. However the passage would be memorable for another reason.

With 500nm to Christmas Island , we saw a very strange effect. The moon was in its 3rd quarter, and so would rise about 6 hours after sunset. As the sun went down, and my eyes began to adjust, it became clear that the sea was brighter than the sky. The guard-rails and lower rigging were faintly, but clearly, silhouetted against the sea. The entire sea was a faintly glowing green as if lit from below. It was like sailing over an illuminated swimming pool. It certainly wasn't a phosphorescence effect as it was persistent and also because the phosphorescence from our wake was barely visible against this "backlight".  I called Henri up, as she had just gone off-watch. Henri, as a rule, does not like "eerie" which this definitely was. The light persisted for all of my watch. When Henri came up for her watch it was about 3 hours after sunset but the horizon was still visible because the sea was brighter and delineated against the sky. We had a quick chat about it - me from my bunk, Henri from the helm, where she asked if it changed at all in intensity (it hadn't), if the contrast in west where the sky was blackest and the sea greenest was due to the moonrise (still 3 hours away) and so on. Then she said, "it's gone", and we appeared to sail right out of the glowing water as suddenly as we had sailed into it. From that point, we then had "normal" phosphorescence until the moon came up on my watch. On the following night, not sure what to expect, and looking forward to our strange light show, we (of course) got nothing.

The last 1088 miles took less than 7 days, which included one night of heaving-to in order to make a daylight arrival on Thursday 17th August. The total trip from Port Vila to Christmas Island was 3,882nm and took us 26d 17hrs.

Some 2 weeks later, while en-route to Cocos, we saw the effect again. It was less visible with a fainter glow and it was soon quenched by the moon-rise. However, having now seen it twice we at least knew it was a real effect! It would take a while to find out what we had observed. After a while we stopped raising the subject, as we struggled to describe it and most sailors thought we were describing a phosphorescence effect.

A description of what we had seen would have to wait for about another year, by which time we were settling back into life in Dublin.

Bizarrely, I was watching the movie “Heat” when the De Niro character – looking out at the lights of LA draws a parallel with Fiji where they have “iridescent algae that light up the sea for miles, they come out once a year, that's what it looks like out there”. Prompted by this I spent some time searching the internet – to see what descriptions of glowing water I could find. I quickly established that the De Niro line was a  bit of screen-writer hyperbole, but I found this description from a Captain Kingman, sailing South of Java (not far from where we were), in June 1854.  

"The whole appearance of the ocean was like a plain covered with snow. There was scarce a cloud in the heavens, yet the sky...appeared as black as if a storm was raging. The scene was one of awful grandeur; the sea having turned to phosphorus, and the heavens being hung in blackness, and the stars going out, seemed to indicate that all nature was preparing for that last grand conflagration which we are taught to believe is to annihilate this material world."

There was also this description:

August 13, 1986. Northwest Indian Ocean

"The entire sea surface took on an intense white glow which was not unlike viewing the negative of a photograph."

from http://www.science-frontiers.com/sf086/sf086g12.htm

In fiction, Jules Verne referred to the phenomenon in his 1870 classic, Twenty Thousand Leagues under the Sea, leading to a conversation between two crew of the submarine Nautilus: 

‘The 27th of January, at the entrance of the vast Bay of Bengal ... about seven o’clock in the evening, the Nautilus ... was sailing in a sea of milk ... Was it the effect of the lunar rays? No: for the moon ... was still lying hidden under the horizon ... The whole sky, though lit by the sidereal rays, seemed black by contrast with the whiteness of the waters. 

“It is called a milk sea,” I explained. 

“But sir, can you tell me what causes such an effect? for I suppose the water is not really turned into milk”. 

“No, my boy: and the whiteness which surprises you is caused only by the presence of myriads of infusoria, a sort of luminous little worm, gelatinous and without colour, of the thickness of a hair whose length is not more than seven-thousandths of an inch. These insects adhere to one another sometimes for several leagues”. “... and you need not try to compute the number of these infusoria. You will not be able, for ships have floated on these milk seas for more than forty miles”.’

Clearly other observers have either been treated to much greater degree of light, or are blessed with greater descriptive powers.

The phenomenon is known as “milky sea” and – according to research by a Professor Herring in University of Southampton - whom we contacted and was delighted with our report - it has been observed 235 times since 1915. 171 of these observations have been in the Northern Indian Ocean and 40 off Indonesia. What once had sailors reaching for metaphysical terms, is now be explained by "free-living bioluminescent bacteria, sometimes present in such enormous numbers that they literally light up huge areas of the ocean”. An analysis of a particularly vivid event described by a merchant ship led a researcher to review satellite imagery which resulted a satellite photograph of the effect off the Horn of Africa. 

I wrote to Prof Herring who,  I think,  was amused by the reference to the movie “Heat” - but like I said at the beginning of the article – its tricky to find out about something you struggle to describe, and when you do, its hard to find someone to take it seriously!  In any case, I think I'm observer number 236!

 There is a good description of the effect and some others at the following address:

  The Mystery of the Milky Sea | BBC Earth