Ushuaia [1] has more than a dozen travel agencies offering excursions in and around Ushuaia, ranging from double-decker-bus city tours (1 hour, US$8) to Parque Nacional Tierra del Fuego [2] (4–5 hours, US$30) and historic Estancia Harberton [3] (8 hours, US$65). They also organize activities such as hiking, climbing, horseback riding, fishing, and mountain biking.
Local operators include All Patagonia (Juana Fadul 60, tel. 02901/43-3622, www.allpatagonia.com [4]), which is the AmEx representative; Canal Fun (9 de Julio 118, Local 1, tel. 02901/43-7395, www.canalfun.com [5]); Rumbo Sur (San Martín 350, tel. 02901/42-1139, www.rumbosur.com.ar [6]); Tolkar (Roca 157, Local 1, tel. 02901/43-1408, www.tolkarturismo.com.ar [7]); and Tolkeyén (San Martín 1267, tel. 02901/43-7073, www.tolkeyenpatagonia.com [8]).
The Compañía de Guías de Patagonia (San Martín 628, tel. 02901/43-7753, www.companiadeguias.com.ar [9]) specializes in trekking.
Links:
[1] http://www.moon.com/destinations/argentina/tierra-del-fuego/ushuaia
[2] http://www.moon.com/destinations/argentina/tierra-del-fuego/parque-nacional-tierra-del-fuego
[3] http://www.moon.com/destinations/argentina/tierra-del-fuego/ushuaia/sights/estancia-harberton
[4] http://www.allpatagonia.com
[5] http://www.canalfun.com
[6] http://www.rumbosur.com.ar
[7] http://www.tolkarturismo.com.ar
[8] http://www.tolkeyenpatagonia.com
[9] http://www.companiadeguias.com.ar