Low tide, tide-mill

This is the rear view of the tide-mill, and definitely doesn´t show it to it´s best advantage: it looks much better at high tide. The mill sits on a tidal estuary. When the tide rises, water floods into the little lagoon, turning the mill-wheels as it goes; and when the tide drops, the trapped water floods back out again, again turning the wheel. I´ve seen another of these in Cantabria, near Santander I think; and another on the Rio Formosa near Faro in Portugal - where apparently there were once dozens, but only one survives. 
The extra photo is of the mouth of the estuary.

http://s3.redmeda.com/biblioteca/lopez_1998_molinos.pdf