Lindblad Expeditions is expanding its reach into the Arctic with plans to grow its National Geographic polar fleet on heightened demand.

The Sven Lindblad-led owner has signed an agreement with Norwegian shipbuilder Ulstein to build a new polar vessel, enlarging the flotilla to four ships in the third quarter of 2021.

The expansion will follow launches of 100-berth National Geographic Quest in July 2017 and 100-berth National Geographic Venture in December 2018.