You can see aerial photos on the link above.
In short, aerial photos of parts of Croatian Adriatic coast (Dugi Otok, Unije and Srakane islands) were done, for the purpose of charting the habitat of Adriatic sea species.
Aaand... there are very clearly visible circles in endemic Mediterranean sea weed, called posidonija (Lat. Posidonia oceanica). That sea weed is dark, grows thick and it is not usual or heard of in this area that it would suddenly die and avoid growing back in sharply edged circles.
It does spread in remotely circular fashion, but it does not disappear like that, at least not by itself.
So no one is sure what happened there, suggestions range from the idea it was something that had to do with recently seen UFO above Unije island, to maybe “fishing” with dynamite (laugh on, there are still few morons that “fish” by detonating dynamite and then scooping dead and knocked out fish from the surface).
Dynamite it is not, locals agree, because these circles are 50 metres in diameter while dynamite does 5 to 15 metres damage.
Also, the distance between circles is very even. It would be an artist, not a poacher, said someone. But it's impossible anyone would poach, artistically, with such abominable amount of explosive needed for so large circles without everyone on neighbouring islands hear it. No one remembers any explosions.
The oil engineers and geologists were contacted too and they confirm such circles do not look like exploration for oil or gas, also, there were no such explorations in the area lately and they would be done in different pattern.
So, what was that that “ate” sea weed, leaving only sand on which no weed grows back? I have no idea.
Edited by Helen of Annoy, 13 May 2014 - 03:39 PM.