Migrants and refugees travelling by sea are not a new phenomenon. Desperate people in all parts of the world have long risked their lives aboard unseaworthy ships and other craft. Some do so in search of work, better living conditions or educational opportunities. Others are seeking international protection against persecution, conflict or other threats to their life, liberty or security. Often this means placing their fate in the hands of unscrupulous, criminal smugglers. In addition to the dangerous conditions in which they travel, many face exploitation, abuse and violence during their journey. This guide describes the international legal obligations, principles and practices applicable to rescuing refugees and migrants at sea.