In the two years since oil reservoirs were discovered off Cuba's coast, Canadian, Chinese, Indian and Norwegian companies have lined up to explore the potentially lucrative Caribbean waters. U.S. oil exploration in Cuban waters - along with most U.S. trade - is prohibited under a 45-year-old U.S. embargo designed to undermine Fidel Castro's communist government. This week, American energy executives meet their Cuban counterparts in the first private-sector oil summit between the two countries. Cubans hope to inform the businessmen of their country's oil potential while undermining the embargo, which has often frustrated American corporations.