They're the South American equivalents of Williams, Ariz.

And why? Because Williams only matters to us tourists -- and only has all those motel rooms -- because a well-known ditch called the Grand Canyon is an hour up the road.

Ushuaia, in Argentina, population 65,000, is a place to eat and sleep and party a little while waiting to grab a ride on an Antarctica-bound excursion vessel or as a base for exploring semi-tamed chunks of Tierra del Fuego. Either plan is a valid reason to rush down here.

Punta Arenas, in Chile, population 115,000, has the closest decent airport to Torres del Paine, the mind-blowing national park a day's drive away. That's reason enough to get down here.

But as towns, well . . .

Cruise ships sailing around Cape Horn stop at one or both, and they deserve that. They would even be worth an extra day if the big boats weren't in so much of a hurry.

That's about it.

Both towns claim to be the world's southernmost, which matters mainly to people who sell mugs and T-shirts and, this being South America, to passionate locals.

On local signage and souvenirs, Ushuaia declares itself fin del mundo -- end of the world. And yes, Punta Arenas, speaking latitudenally, indeed is north of Ushuaia.

Ah, but there are technicalities.

"Ushuaia is on an island," notes a veterinarian who happens to be Chilean, specifically Isla Grande de Tierra del Fuego. Punta Arenas, she further notes, is not. It's on the mainland.

"If we allow islands," she ultimately notes, "there is Puerto Williams." Which is a modest (population 2,000) settlement south of Ushuaia, on a Beagle Channel island, in Chile.

So Chile's Puerto Williams, strictly speaking (and not counting Antarctica, whose largest town is a few shacks with instruments), is at the fin del mundo.

But chances are you won't go there, though you can. The "southernmost" vote here is for Ushuaia, but the restaurants are a little better in Punta Arenas, which, in the fin, is all that matters -- aside from both being surrounded by Tierra del Fuego and the rest of Patagonia, which counts for something.

And one last point:

Both Ushuaia and Punta Arenas have accessible penguins.

Ushuaia

If you don't mind how far it is from everything, the setting is nice. It's on the Beagle Channel, which separates Isla Grande de Tierra del Fuego (which is half in Chile, half in Argentina) from Isla Navarino (all Chile's), and is framed most of the time by snow-dusted peaks.

In the era before regularly scheduled airline service, it was home to a prison -- location, location, location -- and was a lively port for exporting wool, timber and a little gold. The prison closed in 1947 and is a museum, the gold didn't last, timber is scarce these days and the wool business isn't what it was, which leaves tourism as the primary local industry.