The fish market in Santander (or as its called - Mercado de la Esperanza) is one of the most spectacular markets in northern Spain. Mercado de la Esperanza translates to Market of Hope - it was designed in 1897, and is a proof of iron architecture preservation in the 19th century in Spain. This market is in the center of Santander, and the most popular items on sale are fish and shellfish.
The next question asked by anyone who knows me would be "What the hell were you doing there?". Good question - I kind of got dragged into it by other people I was with. But regardless of that, I have always thought food to be a very important cultural indicator of a place, and in this case, fish/seafood are a very big part of Santander/Cantabrian social infrastructure - so I thought a visit was warranted. It is chaotic, like any good market would be, and the smell is strong (if you don't like fish). In fact, when we visited, it was packed with people buying seafood for New Years Eve Dinner because a big family meal is tradition, and what better to fill the plates with than fresh fish right from the nearby ocean.