The 66.7% equity stake, valued at $1 billion, expands Royal Caribbean’s portfolio to increase trips with some of the most exclusive, ultra-luxury offerings on the high seas.

Silversea Cruises specializes in luxury all-inclusive voyages to Antarctica, the Arctic, and Greenland. Across the company’s nine ships, most tickets start at $5,000. A private balcony suite comfortably accommodating three on a Galapagos Islands cruise recently listed for $11,900. The company also runs waitlists for suites aboard ships bound for in-demand destinations such as the Norwegian fjords.

By contrast, tickets for suites with Royal Caribbean’s most exclusive brand, Azamara Club Cruises, top out around $3,000.

Silversea majority owner, Manfredi Lefebvre D’Ovidio, will stay on as executive chairman of the company that his father founded in 1994. Silversea CEO Roberto Martinoli will also stay on to oversee Silversea’s management team.

Royal Caribbean chairman and chief executive Richard Fain spoke about the value of offering even more high-end features from both oceangoing companies. “Ultraluxury and expedition cruises are gaps in our portfolio today,” he said on a conference call. “Uniting our two companies presents an extraordinary opportunity to expand vacation options for guests and create revenue in strategic growth areas.”

In 2017, Royal Caribbean had almost $9 billion in revenue.