Short of Antarctica itself, some of the Southern Hemisphere’s most awesome scenery occurs in the Beagle Channel and southern Tierra del Fuego. And as usual, Charles Darwin left one of the most vivid descriptions of the channel named for the vessel on which he sailed:
The scenery here becomes even grander than before. The lofty mountains on the north side compose the granitic axis, or backbone of the country, and boldly rise to a height of between three and four thousand feet, with one peak above six thousand feet. They are covered by a wide mantle of perpetual snow, and numerous cascades pour their waters, through the woods, into the narrow channel below. In many parts, magnificent glaciers extend from the mountain side to the water’s edge. It is scarcely possible to imagine anything more beautiful than the beryl-like blue of these glaciers, and especially as contrasted with the dead white of the upper expanse of the snow. The fragments which had fallen from the glacier into the water, were floating away, and the channel with the icebergs presented, for the space of a mile, a miniature likeness of the Polar Sea.
Even today, few visitors see Tierra del Fuego’s splendid fjords, barely changed since Darwin described them in 1833; many do so onboard excursions from Punta Arenas  to the Argentine port of Ushuaia  or back on the twin Chilean vessels Mare Australis and Via Australis.
Unlike the Navimag ferry from Puerto Natales  to Puerto Montt , these are cruises in the traditional sense—the passengers are waited on hand and foot, and they’re not cheap. Yet for the foreseeable future, this remains the only way to see the area short of sailing your own yacht or chartering someone else’s, and for that reason it’s worth consideration even for those with limited finances.
Though it’s possible to do the entire loop from either Punta Arenas or Ushuaia, most visitors do either four days and three nights from Punta Arenas to Ushuaia, or five days and four nights from Ushuaia to Punta Arenas. The boats sometimes undertake variants that involve four nights from Punta Arenas and three from Ushuaia, and there’s usually some duplication; both legs, for instance, visit the western Beagle Channel’s Glaciar Pía, and sometimes the boats are there simultaneously.