As Ivan T. Sanderson highlights in his Invisible Residents: The Reality of Underwater UFOs, there are a large number of UFO sightings on, in and under the water - which should be no surprise as there planet is covered in the stuff it just tends to be about as thinly populated as Kojak's head. Of course, there are presumably many explanations for the strange lights (even if you think most of them are caused by our alien brethren commuting from their undersea lairs to torment so redneck's private parts, some are going to be the product of other phenomena) and with that in mind I want to look at a couple of reports:

Recently we reported a UFO sighting in Argentina involving a number of UFOs seen rising from a lake in the province of Entre Rios on January 2 2009 by numerous witnesses. Now we have received reports of a very similar sighting in Indonesia. The parallels are striking and raise many questions.

A group of eight friends planned to go to a concert in the centre of the regional city of Jember in East Java on December 20 2008. Tickets to the concert were sold out so the group headed back to one of their homes in two cars. Heavy traffic in the centre of the city forced the group to go an alternative route past a lake on the outskirts of the town. One of the cars halted as the driver spotted a remarkable sight above the small lake that they were passing.

Two large lights rose from the lake, one white and one red. Two beams were then shot from the lights towards the lake and at that point the lights appeared to change formation; this lasted no less than ten minutes before the strange lights shot off upward into the night sky.

Source

Hat tip

This earlier report they refer to is:

One of the most recent sightings occurred on January 2 2009 starting at around 11pm. Witnesses are reported to have seen at least three UFOs. The first emerged from the body of water known as Laguna Del Pescado and then sped towards the fields surrounding the regional city of Victoria. A second large white light then appeared in the sky, parallel to the moon, before turning west and speeding upwards away from earth. Finally another light then appeared and did the same-the lights ranged in colour from white, blue, red orange and yellow.

The UFOs were seen by multiple witnesses from a number of viewpoints and police were contacted. One witness noted that they did not behave like Chinese lanterns, flares or fireworks but rather like controlled craft.

Source

The thing this (and in particular the first report) reminds me of are the Naga fireballs which rise from the river in Thailand and is something I'd love to see one day. Is there a simple/natural explanation for them?

Well I was impressed by one idea that what could trigger the ignition is the presence of naturally-occurring phosphine (also known as phosphane) as discussed in The Shocking History of Phosphorus: A Biography of the Devil's Element (2001) by John Emsley (apologies for any errors I scanned/OCRed it in when I borrowed the book from the library) in a discussion of will-o'-the-wisps pages 286-289 (although his broader aim is to find a natural explanation for Spontaneous Human Combustion:

It has always been the received wisdom of chemistry that there was no way in which phosphate (PO₄^3-) could naturally be changed to phosphane (PH₃). Such a change defied the laws of oxidation-reduction reactions, as well as going against the energy difference between these two species. Nothing in the natural world had the power to replace four, immensely strong phosphorus-oxygen bonds with three feeble phosphorus-hydrogen bonds. Even in the laboratory there was nothing that chemists had come across that was able to accomplish this conversion in a single step, and they came to believe that it must be impossible. In any case, such large quantities of energy would be required to make it happen that no natural system could have evolved that had the power to carry it out.

These assertions made it difficult to explain the phenomenon of Will-o'-the-wisp, those curious lights that flit across marshes at night. The early chemists had collected marsh gas that bubbled to the surface from bogs and stagnant waters and had shown that it was methane (CH₄). This would provide the fuel for the lights, but what caused the methane to ignite? Spontaneously flammable phosphuretted hydrogen seemed to provide the answer. The anaerobic conditions of a marsh that turned decaying organic matter to CH₄ could clearly convert phosphate to phosphuretted hydrogen. It seemed a logical explanation, but later chemists declared it impossible.

In fact it was the chemists who were wrong. Nature may be governed by the laws of chemical thermodynamics, but she often seems to ignore them. The production of phosphane and diphosphane is a case in point. Despite the received wisdom that it was impossible to produce phosphane in natural systems, some chemists reported that they had detected this gas in sewage sludge and in the sediment at the bottom of harbours. While this was puzzling, it was not entirely inexplicable: it might have come from industrial waste. However, the natural formation of diphosphane with its phosphorus-to-phosphorus bond was nigh on impossible, surely? Microbes knew otherwise.

In 1993, Gunter Gassmann and Dieter Glindemann, of the Helgoland Biological Institute in Hamburg, discovered that micro-organisms could make phosphane and diphosphane after all. They published their research in the leading European journal of chemistry, Angewandte Chemie, International Edition in English. Gassmann and Glindemann concentrated on the anaerobic natural environment that exists within the gut of cows, where copious amounts of methane gas are formed.

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Their research does not answer the question of why phosphane is produced, or how, but clearly there is a microbe with the necessary combination of enzymes to effect this remarkable transformation. However, their research did explain the Will-o'-the-wisp phenomenon. The scientific name for this is ignis fatuus. It might even explain ghosts, especially where a cemetery is located on water-logged land. It is not impossible that graves and coffins would fill with water and the putrefaction would generate methane along with phosphane and diphosphane. The reports of ghostly apparitions emerging from graves was capable of rational explanation after all.

So there is potentially for some of the anomalous lights emerging from bodies of water to be formed by anaerobic conditions in the sediments and it is certainly an interesting area for further investigation. Especially as quite a few people are sceptical of the chemstry, see for example this article on Hunting Spooklights (love the idea of a Ghostbusters-style kit to hoover up a will-o'-the-wisp!!). It is also too close to the old Swamp Gas explanation for some people's comfort, I'm sure.

Equally it can't hope to explain all UFOs seen around bodies of water, but few people would suggest that every strange light has to have the same explanation (if so they'd be setting themselves up for a disappointment) and I suggested another theory for lights seen over reservoirs. As mentioned in that entry the Skinwalker Ranch episode involves lights diving into and out of the local reservoir and it is unclear if there is an easy explanation for that.

Emsley's books is well worth a read too - it is a wide-ranging "biography" of an element that touches on a lot of history as well as stranger subjects like SHC and is the kind of interesting and engaging science book that they all should be like.