Video posted at BoingBoing this morning. No answer there (yet) as to why these interconnected circles were created in what appears to be tidal mud flats. Are they weirs? Evaporative catchments for mineral extraction? What???
Location said to be near Isla Aguada (Campeche) in Mexico. Note the immense extent of the structures. The connecting "canals" appear to have been created or enhanced with large earth-moving equipment. Some look fresh, and there are what looks like older ones that have silted in.
This blog has amazing readership. I suspect someone will know or can research the answer.
Solved within three hours! (answer in Rocky's comment)
Addendum: Here's an interesting screencap I made from the map of the Democratic Republic of the Congo linked in jschmidt's comment:
Fascinating. There must be more information somewhere...
Addendum: Found some relevant information in a video about mangrove restoration in Thailand (relevant part at the 7:40-8:40 segment or so). Apparently those drainage channels are dug by hand with shovels.