Puerto Río Tranquilo [1]’s best excursion is a launch trip to Capilla de Mármol, a string of swirling marble grottos on the shoreline. The 1.5-hour trip costs around US$35 for up to five persons, but it’s difficult if winds are high. Ask at Hostal Los Pinos to hire a launch.
It’s best in late summer or fall, when water levels permit launches to approach more closely and explore more thoroughly.
Links:
[1] http://www.moon.com/destinations/chile/northern-patagonia/-southern-carretera-austral/puerto-rio-tranquilo