The Grand Erg Oriental is the great eastern sand sea of the Algerian Sahara — a 600-kilometre stretch of dunes that extends across the border into southern Tunisia. El Oued sits on its northwestern edge, which makes the town the most practical base for trips into the sand from anywhere in Algeria.
Local agencies and accommodations can arrange guided excursions ranging from a few hours (drive out, sunset on a dune, drive back) to multi-day camel trips with overnight bivouacs in the dunes. The standard short itinerary heads south or east of town to reach the big dunes within an hour. For anything overnight, you need a competent guide and proper provisions — temperatures swing from blistering afternoons to genuinely cold nights. The best months are November through March; summer is brutal and most of the local agencies suspend trips.