Saber-rattling political interests surround the Strait of Gibraltar. Britain, far from home, keeps a hand in the Mediterranean maritime game by clinging to Gibraltar, much to the frustration of Spain. For its part, Spain controls Ceuta, a tiny spit of land at the edge of Morocco, over Morocco’s objections. The United States maintains military bases in the region and its planes, along with Spain’s, patrol the skies overhead. All these forces are here to protect shipping: Fully half of the world’s trade passes through this narrow channel every year, as well as a third of its oil. Are those roiling currents beneath your ship beginning to feel like a metaphor for the local politics?