Most ships need a berth. A few of Silversea’s do not, and that single difference opens up a list of places you cannot otherwise reach: a beach in Greenland, a bay in the Galápagos, a stretch of Antarctic coast with nothing on it but penguins.
You go ashore by Zodiac, with an expedition team who have spent their careers in these places, and you come back to a suite, a hot shower and a butler who has already run the bath.
Expedition travel without the hardship. That is the trick Silversea pulls off better than anyone.