What becomes the Gulf Stream comes up throught the Campeche straits, turns ENE thru the Florida straits, then heads north along the east coast of Florida as the Gulf Stream. Generally during the spring-summer months, there is an off-shoot known as the "Loop Current" which continues northward across the Gulf of Mexico toward the Mississipi Delta area, then loops around to the east and heads south again to rejoin the main current flowing ENE though the FL straits. The loop current exhibits great variability in its northward penetration and intensity. It was regular enough, however, that sailing ships knew of it and tried to "ride" the southward flow when outbound from New Orleans, and the northward flow when enroute to NO. As noted in Dave's post above, turning the corner around the end of the FL keys too tightly was perilous indeed.