Nationals of Libya, Algeria, Tunisia, Syria, Côte d’Ivoire, Mali, Senegal, Niger, and the Gambia and do not require a visa to get in Mauritania, while holders of passports of other countries can get the Visa on arrival at Nouakchott International Airport (Oum Tounsi). Single entry fee is 55 EURO, but it costs 125 EURO for double entry.
Overland travelers can also get the Visa in Rabat, Senegal, and Banjul in Gambia. You are required two passport-size photos, as well as a copy of the information pages of your passport. While it only takes on day to be issued in Rabat, it sometimes takes up to three days at the Mauritanian embassy in Dakar, Senegal.