Fishing harbor with Senegalese boats. Also, there are many shipwrecks in the Nouadhibou Bay. The biggest and most recent shipwreck lies at the tip of the peninsula.
At the absolute southernmost tip of the same peninsula, there is a small national park, where for a small fee you can observe the meeting point between the bay and the Atlantic Ocean. The point is home to several monk seals. Some of them have been aggressive, so keep a safe distance.
Between the Port Autonome and Cansado are the ruins of an old French coastal gun emplacement designed in its day to protect the French colony from the Spanish border a few kilometres away. There is no fee and no guide. There are underground tunnels which connect the 15 meter high gun towers. Some tunnels drop off dangerously! A torch or flashlight is helpful.
You might be tempted to visit the old Spanish buildings at the little town of La Guera on the southern peninsula. It's not actually in Mauritania, but a disputed territory just to the west of Mauritania, so exploring the historic site technically requires an official border crossing. There is now a Mauritanian military post nearby. If interested, check with local authorities first.
The down town market, in Keran, behind the main middle road, is full of little shops selling a surprising variety of things from all over the world. It has a well stocked chep-chep or second-hand market. You can find prizes for next to nothing.
