Royal Caribbean (RCCL) is expecting "significant synergies" after agreeing to take a $1bn controlling stake in luxury and expedition cruiseship company Silversea Cruises.

The US giant said the deal for a 66.7% holding will propel the growth of the brand.

The move was announced by RCCL and Silversea chairman and owner Manfredi Lefebvre D'Ovidio.

It brings together two companies with "bold, long-term visions for the cruise industry," they said.