Peter Boller and I took these photos on a trip from Dakar through Nouakchott, Atar, and Nouadhibou in 2018. They are arranged chronologically- starting from the Senegal/Mauritania border, going into the deep Sahara, riding the iron ore train to the coast, and then returning down the coast to Senegal. Read the full story of the trip here; or, watch a video of the train ride at dawn here.