Mauritania Airlines flies daily (except Wednesday) to Nouakchott (UM31,000, 45 minutes; departure times vary), and three times a week to Casablanca in Morocco and Las Palmas in the Canary Islands (round trip UM161,500). Tickets can be purchased at the airline office or at any one of the handful of travel agencies around town.
There are plenty of minibuses and bush taxis to Nouakchott (UM5000, six hours); the former, of course, are more comfortable and leave from various company offices around the city. Premiere Classe is recommended – best to book a day in advance.
You can get transport from here to Morocco (Western Sahara). Cramped bush taxis go to the border (UM3000 to UM5000 per person) or direct to Dakhla (UM12,000, eight hours). Arrive early – any later than 8am and you'll be facing a long wait for the vehicles to fill and go. Taxis leave from a 'station' at the northern entrance to Nouâdhibou near the Bureau de la Fédération des Transports. Another good option is to travel to the border and board a bus to Dakhla (MAD 150, daily 2pm); a taxi (these tend to be in relatively good condition and comfortable) from the Moroccan side of the border to Dakhla is around MAD 400.
There is a train that runs from Nouâdhibou to Choûm and Zouérat (UM3000). The train 'station' is about 5km south of town.