West of Ushuaia some 12km along RN 3, Parque Nacional Tierra del Fuego was Argentina’s first coastal national park. Its 630 sq km span from the Beagle Channel to the south to beyond Lago Fagnano in the north. For information, visit the Centro de Visitantes Alakush.
There's public access to the southern edge of the park, with short, easy trails designed more for day-tripping families than backpacking trekkers. The rest is protected as a reserva natural estricta (strictly off-limits zone).
Despite this, a few scenic hikes along the bays and rivers, or through dense native forests of evergreen coihue, canelo and deciduous lenga, are worthwhile. For spectacular color, come in autumn when hillsides of ñire glow red.
Birdlife is prolific, especially along the coastal zone. Keep an eye out for condors, albatross, cormorants, gulls, terns, oystercatchers, grebes, kelp geese and the comical, flightless, orange-billed steamer ducks. Common invasive species include the European rabbit and the North American beaver, both wreaking ecological havoc despite their cuteness. Gray and red foxes, enjoying the abundance of rabbits, may also be seen.