you may want to read this before you head down there. These guys are serious.
ENTRY/EXIT REQUIREMENTS/TRAVEL TRANSACTION LIMITATIONS: The Cuban Assets Control Regulations are enforced by the U.S. Treasury Department and affect all U.S. citizens and permanent residents wherever they are located, all people and organizations physically in the United States, and all branches and subsidiaries of U.S. organizations throughout the world. The Regulations require that persons subject to U.S. jurisdiction be licensed to engage in any travel-related transactions pursuant to travel to, from, and within Cuba. Transactions related to tourist travel are not licensable. This restriction includes tourist travel to Cuba from or through a third country such as Mexico or Canada. U.S. law enforcement authorities have increased enforcement of these regulations at U.S. airports and pre-clearance facilities in third countries. Travelers who fail to comply with Department of Treasury regulations could face civil penalties and criminal prosecution upon return to the United States.