"Cuba is the largest country in the Caribbean, so there's some exciting possibilities," said Carnival spokesman Roger Frizzell, noting that there are ports and some cruising infrastructure already on the island.

The news sent the value of Herzfeld Caribbean Basin (CUBA) soaring 35%. It's a mutual fund that's invested in companies likely to benefit from increased trade with Cuba, such as cargo-ship operator Seaboard Corp. (SEB) and Watsco 

(WSO), which would distribute air conditioning equipment to the tech-challenged island.

American companies that make consumer products -- such as soap and packaged foods -- are likely to benefit first, said Andres Diaz, a former Obama administration trade official who now does management consulting in Latin America. 

They're inexpensive, and the Cuban population can't currently afford much.

"And we'll be seeing these legendary Cuban products -- like cigars and rum -- circulating in the U.S.," he said. Although the embargo persists, travelers can now return to the United States with $100 worth of cigars or alcohol and $400 of any other item.

Also, Cuban-Americans can now send more money back to family and friends on the island, given that Obama has risen the cap on remittances. And there's a lot of potential for telecommunications companies to connect more Cubans to the Internet.

A national trade group of American farmers -- who notably receive U.S. government subsidies that make their products cheaper for foreigners -- says they'll stand to benefit if banking and credit restrictions are lifted.