Take the adventure of a lifetime this December with an 11-night cruise to Antarctica. In this sale in which the second passenger travels for free, prices are cut in half, working out to US$4948 per person. That's a saving of $9896 per couple, which can instead be put toward airfare.

Board in Ushuaia, Argentina, then begin the voyage by crossing through the Drake Passage before reaching the South Shetland Islands and Antarctic Peninsula. Excursions allow travelers to walk around this incredible landscape and look for wildlife, including penguins, humpback whales and leopard seals. Click here to see the full itinerary.

The deal includes:

• Accommodation in a Main Deck Window cabin
• Shipboard breakfasts, lunches and dinners
• Shore landings and excursions
• Professional expedition leadership including educational presentations

Valid on the Sea Adventurer for travel departing Dec. 15. Other cabin types available -- inquire when booking. A similar itinerary is available aboard the Ocean Diamond departing Jan. 13.

Part of a larger sale, the buy-one, get-one-free offer is available for four departures of two Antarctic itineraries, including 20-night trips departing Dec. 11 and 26, that also take in South Georgia and the Falkland Islands starting at $9498 per person.

Note: All other 2012-'13 Antarctic sailings are available for 50% off the second passenger. See the landing page below for details.

Travelzoo Tip: International flights are not included, but Quark Expeditions can arrange flights when booking.