Thousands of seafarers remain stranded at sea while cruise majors grapple with the US Centers for Disease Control's (CDC) stringent repatriation protocols amid the coronavirus pandemic.

The federal agency requires shipowners to agree to send crew home, without using any public transport, before letting them back on land.

Royal Caribbean Cruises has already repatriated some seafarers through commercial and charter flights and direct sailings but is unwilling to send them home through private travel means, spokesman Jonathon Fishman said.