The best-known among them are Puerto Deseado (Port Desire) at the mouth of the Deseado river (1253 m.), Santa Cruz, at the mouth of the Santa Cruz river (1481 m.), and Ushuaia, on Beagle Channel, Tierra del Fuego.
The division of the archipelago to the south of Beagle Channel includes the islands of Hoste, Navarin, Gordon, Londonderry, Stewart, Wollaston and numerous islets, disposed in triangular form with the base on Beagle Channel and the apex at the rocky headland of Cape Horn.
Cattle farms prosper along Beagle Channel, the timber industry is growing, lignite seams have been discovered, and alluvial gold is washed principally at Slogget Bay.
The latter, as regards its main chain, is on the northern coast of the Beagle Channel, in Tierra del Fuego, bounded on the north by the deep depression of Lake Fagnano and of Admiralty Sound.
Although on ordinary maps this region presents to the eye a hopelessly confused aggregate of islands, channels and fjord-like inlets, it is nevertheless clearly disposed in three main sections: (1) the main island; (2) the islands to the south, from which it is separated by Beagle Channel; (3) the islands to the west, marked off from those to the south by the Brecknock Peninsula.
The Port Moresby beds are Cainozoic. They are highly inclined, and occupy a large range of country along the south coast, and include the Macgillivray Range, to the north-east of Beagle Bay.
At its west end Beagle Channel takes the name of Darwin Sound, which leads to the Pacific at the Londonderry and Stewart Islands.
The boundary between Argentina and Chile has been settled in such a manner that Argentina holds that part of the main island of Tierra del Fuego which is situated east of the meridian of Cape Espiritu Santo, the frontier striking the north shore of Beagle Channel about its centre; and Chile holds all the western part of the main island and the other numerous islands to the west and to the south of Beagle Channel.