The Caribbean country's National Drug Control Agency says the boat was heading toward a bay west of the capital Sunday when it was detected by the U.S. Drug Enforcement Administration.
The DEA reported the suspicious vessel, and three Dominican aircraft and four military boats began pursuing the speedboat. The Dominican anti-drug agency says the traffickers threw bales of cocaine into the sea in international waters during the chase and escaped.
Members of the U.S. Coast Guard recovered the drugs and sent them to the U.S. island of Puerto Rico.
Earlier this month, Dominican authorities confiscated a cocaine load of 1,870 kilograms (4,122 pounds) from an abandoned boat in the same bay.