Carnival Corp and Royal Caribbean Cruises plan to join forces on the popular cruise destination of Saint Lucia in the Caribbean.

The two US cruise majors have signed a memorandum of understanding (MOU) with Saint Lucia's government to form a joint venture to build and run a new cruise port in Vieux Fort.

The Vieux Fort facility on the island's southern side will be able to "accommodate the latest and most innovative ships in the cruise industry", Arnold Donald-led Carnival said.