Patricio Guzman, who chronicled the military coup against Salvador Allende in his documentary trilogy The Battle of Chile (1975-’79), has begun, in old age, to process his political experiences through stunning personal essay films about the geography and astronomy of his native land. Nostalgia for the Light (2011) considered the heavens as viewed from two observatories in the Atacama Desert, where General Pinochet’s men buried the bodies of political enemies; in this excellent companion piece Guzman ponders the endless Chilean coastline, particularly the waters where some 1,200 Allende supporters were tied to rails and sunk. He also visits the Tierra del Fuego archipelago, at the southernmost tip of the country, and speaks with descendants of the Yaghan and Alacalufe tribes who were targeted for extermination by European settlers. Guzman makes his most important contribution, though, as a personal witness connecting all these things; as one oceanographer reminds him, thought is also fluid. In Spanish with subtitles.