The Coast Guard reported Friday that it boarded an illegal charter boat operation that took seven paying passengers on a four-day round-trip cruise from Charleston to Savannah.

The names of the vessel and the captain are not being released for now because of an ongoing investigation, the Coast Guard said.

The operator had an expired Coast Guard-issued captain’s license and the vessel did not have a valid certificate of inspection, which is required for all commercial voyages with more than six passengers, according to the Coast Guard.

“Illegal operators put lives at risk by sidestepping safety requirements,” said Capt. Ric Rodriguez, commander of Coast Guard Sector Charleston.

A boat carrying more than six passengers is required to have a Coast Guard certificate of inspection that is displayed in an area accessible to passengers.

Those with concerns about an illegal charter can call Coast Guard Sector Charleston at 843-740-7050.