Bordering the Parque Nacional Torres del Paine on the southwest, Parque Nacional Bernardo O'Higgins marks the southern tip of the vast Campo de Hielo Sur (Southern Ice Field). As it is inaccessible by land, the only way to visit the park is to take a boat up the Seno Última Esperanza. The Navimag boat passes through on the way to Puerto Montt, but only the Puerto Natales–based, family-run outfit Turismo 21 de Mayo operates boats that actually stop here—the 21 de
Mayo and the Alberto de Agostini. (Several operators run trips to just the Balmaceda Glacier.) These well-equipped boating day trips are a good option if for some reason you don't have the time to make it to Torres del Paine. On your way to the park you approach a cormorant colony with nests clinging to sheer cliff walls, venture to a glacier at the foot of Mt. Balmaceda, and finally dock at Puerto Toro for a 1-km (½-mi) hike to the foot of the Serrano Glacier. Congratulations, you made it to the least-visited national park in the whole of Chile. In recognition of the feat, on the trip back to Puerto Natales the crew treats you to a pisco sour (brandy mixed with lemon, egg whites, and sugar) served over a chunk of glacier ice. As with many full-day tours, you must bring your own lunch. Warm clothing, including gloves, is recommended year-round, particularly if there's even the slightest breeze.