You should really visit
I spent many years taking summer vacations in the area and the truth is that its unique beauty never ceases to amaze me.
The Santoña, Victoria, and Joyel Marshes National Park is a protected space in Cantabria and one of the most important wetlands for water-birds in northern Iberia. It's a fundamental stop for the winter migration of many bird species.
You can also see several mills for harnessing tidal power (there were once 20 in the Santoña area, all used to generate energy from the movement of the tides).