From the Muelle Turístico, at the foot of Lasserre, there are boat trips to Beagle Channel wildlife sites such as Isla de los Lobos, home to the southern sea lion (Otaria flavescens) and the rarer southern fur seal (Arctocephalus australis), and Isla de Pájaros, a cormorant nesting site.
These excursions cost around US$40 pp for a 2.5-hour trip on oversized catamarans such as the Ana B, Ezequiel B, and Luciano Beta. With extensions to the penguin colony at Estancia Harberton [1] and a visit to the estancia itself, the cost is about US$68.
Rumbo Sur and Tolkeyén sell tickets for these excursions from offices at the foot of the Muelle Turístico, where Héctor Monsalve’s Tres Marías Excursiones Excursiones (tel./fax 02901/42-1897, www.tresmariasweb.com [2]) operates four-hour trips (US$43–52 pp) on smaller vessels (four passengers minimum, 10 maximum) that can approach Isla de Lobos more closely than the large catamarans. They also land on Isla Bridges, a small but diverse island with cormorant colonies, shell mounds, and even the odd penguin.
Links:
[1] http://www.moon.com/destinations/argentina/tierra-del-fuego/ushuaia/sights/estancia-harberton
[2] http://www.tresmariasweb.com