Thousands of Yemenis have fled across the Bab al-Mandab Strait (the narrow waterway separating Yemen from the Horn of Africa) by boat over the past ten days, driven by a Houthi offensive targeting a key island and the strategically vital port of Mokha. Refugees are arriving in Obock, a small port town in Djibouti, where officials are bracing for as many as 10,000 people. The UN's International Organisation for Migration has warned that many are travelling on overcrowded boats with dangerously limited supplies of food and water.