With their sheer cliffs and water-filled valleys, fjords are a stunning reminder of the transformative power of ice. These sea passages slice through coastlines in and around the planet’s polar regions, revealing a map of the places glaciers once grew. Though united in their geology, the fjords of the world are surprisingly varied: some provide safe harbor to snug fishing villages, while other, less hospitable channels are choked with active glacial ice year-round.

Whatever the backdrop, sailing through a fjord is a thrilling journey through millions of years of geological change. From the granite cathedrals of Chilean Patagonia to the sloping coastal forests of Alaska, here are six places where you can experience the majesty of a fjord directly from the ship's deck on a voyage with National Geographic-Lindblad Expeditions.