A mystery is always fun to poke the brain at. Considering the fact that ices will be heavier than the liquid on Titan, this might be the buildup of ice on a reef of ices right under the surface. The hypothesis that it might be foam is one I could have liked, but it is bright, which make that alternative less likely.

Try solid ice-foam. Closed cell ice foam on the lake bed would be buoyant in methane. Either it could be formed currently by being erupted from the seabed in some cryovolcanic process or it could be there already just waiting for some disturbance to dislodge it so it can float up.

Solid ice-foam is a good suggestion, and I'd really like to get the idea to float.

But the process would need to be just right to create foam bubbles of the right size and thickness to make all parts of this island buoyant.
Now that the total size is rather large, this mechanism creating the bubbles would also have to work evenly over a sizeable part of this feature.

So I am stuck in the icy reef, and the ice hypothesis here. =)

Here's my thinking. Radar bright means a polar material like ice. Methane-buoyant ice means closed cell foam, like pumice. On Earth, floating pumice disperses due to winds and currents, then eventually washes ashore or sinks as its cell structure breaks down. That seems to fit with what we're seeing.

How would a closed cell ice foam form? I don't know, but here we are on a world with a wide range of aqueous and organic materials. The occasional presence of some suitable surfactant when the material solidifies is not too much to ask.

Newly exposed shoals can I think be eliminated. The liquid level hasn't changed much if at all, and anything shallow would already have been visible whilst just below the surface. There was no hint of it before the 'island' first appeared.

(Note: porous materials, thought to be common on Titan, can be either permeable like sponge or impermeable like expanded polystyrene,)

More 'magic islands' - and more bathymetry - in Kraken Mare this time: http://photojournal.jpl.nasa.gov/catalog/PIA19047

(from the Cassini website) http://saturn.jpl.nasa.gov/news/cassinifea...eature20141110/

It's the Nautilus of captain Nemo!

I hope it's an unexpected an uniquely Titanian emergent property of the physical and chemical properties of the stuff in the lakes - something truly unique to Titans bizzare environment would be amazing!

It would be interesting to see if there are any surface temperature changes over time at these sites. However, and please correct me if I'm wrong, I don't think that there's any way to obtain data like that at a useful resolution for these features unless they are very pronounced changes.

It sets the mind racing, that's for sure. It reminds me of the uncomprehended phenomena, some benign and some dangerous, on Stanislaw Lem's imagined world Solaris.

The important thing here is the statistics of two. Just one is a remote possibility, but there are never just two of anything. Two in a relatively small sample of the liquid surface in both space and time means that these things pop up quite a lot. I'm left wondering about parts of the lakes and seas that have been imaged only once. Could a few of those other islands be 'magic' ones too? Do the radar images of the 'magic' ones differ in any way that would allow us to distinguish? I also wonder about the lake coastlines. Are there undetected inlets covered with rafts of flotsam disguising the outlines?

Luckily there's VIMS as well as SAR this time, so expect a good science harvest!

I have a thought that has been itching me all day, and I'd like to clear it out: Could these magic islands be tension wrinkles in a membrane that sits on top of the lake surface? If the lakes develop a fairly thick layer of something semi-solid, it might buckle and then relax as changing environmental conditions alter the overall tension. The specular reflections observed could be due to a thin liquid layer on the surface. It just struck me when my tea went cold that the patches of wrinkles on the skin looked a bit like the 'island'...

It has been said that some lakes or seas were almost as smooth as a mirror. As you say, why not a thin membrane over le liquid.

A new radar-bright feature about 50 km wide. Difficult to understand!

I see several hypotheses:
--> a detached chunk rising from the sea floor.
--> rising bubbles from hot springs
--> a new island via cryovolcanism
--> snow fall or fall of hydrocarbons or organics (some clouds have been seen over Ligeia Mare)

--> or perhaps, some submarine topography (close to the surface) can be discerned if the incidence angle from the radar mapper is low ( as deduced from the data of the Cassini Huygens website).
...
But the bright structures seem to evolve rapidly. Only plankton formations can change so quickly !

Here is a terrestrial 'magic island', no plankton required!
http://www.google.co.uk/imgres?imgurl=http...t=0&ndsp=12
I'm referring to the pumice raft not the new island there.

But I like the wrinkles suggestion for the degree of lateral thinking involved.

MOD NOTE: Let's please remember that rule 1.3 also doesn't permit discussion of plankton...

I have given the hypothesis of marsbug some thought, and considering the possible chemistry of the lakes that could hold dissolved organics that indeed might bond into something of the kind.
An oily organic substance is also possible, it would also dampen waves, but would it be to heavy float?
Lastly we have the foam proposed by the scientists involved in these studies, yes it would float, yet if there's any wind it would move.
Regardless of those alternatives, I label the idea by marsbug a plausible alternative.

On the evidence of the recent re-observation of the Ligeia example (post 59) they do move, very slowly and mainly shorewards. That one also spread out over a wider area and faded somewhat after some months. I find it hard to imagine either waves or wrinkles hanging around in the same location for that long.