In Northern Europe, spa culture includes running from the sauna, through the snow, and back, an experience that shocks and invigorates. Now, cruisers can have a similar experience at sea. 

Viking Ocean Cruises' Viking Star has what just may be the best spa on water: Inside you'll find handmade products for sale, and a killer thermal suite that is not only co-ed, but complimentary to all passengers (and not just those booking spa treatments). The gorgeous suite, which is lined with cool grey stone and lit by a long, elegant fireplace, includes a Scandinavian-style bucket shower, sauna, steam room, resistance pool, and whirlpool tub as well as the most talked about new feature: The Snow Grotto. 

What It's Like: The first of its kind at sea, the Snow Grotto is small but a fun novelty to try. Inside the tiny blue-lit room, you'll find snow on the floor as well as on the bench, and an undeniable chill in the air. After a dip in the hot tub or the sauna, the change in temperature is dramatic as you ease into the space, and bracing. Only a few people can fit at a time, but we never had to wait or saw a line form on our sailing. That said, it's cold — really cold. We recommend wearing flip-flops, and having your robe waiting on the hook outside the door.

The Verdict: Is the grotto going to be your favorite amenity on the ship? The thermal suite may be — or perhaps the food? — but unless you grew up in Northern Europe embracing the sauna culture, the grotto probably won't be. Still, since it's free, it's certainly a fun addition to your cruise ... and it's a great photo op.