Every sanitation system in the world somehow ends at sea. Some systems are more sophisticated, others are less. But if your underwater pipe gets far enough from the shore, you don’t see the results… at least at first sight. It is like hiding something under the rug…

How thick the rug? On the next image, generated using the General Bathymetric Chart of the Oceans published by the British Oceanographic Data Center, you can see the depth (in meters) of the underwater spaces under the Iberian peninsula. The dark brown hues are areas less than 200 m deep (the height of the highest buildings in the peninsula). It is also a dimension previously used in a game here at metrhispanic, albeit in the opposite sense…