Aisén Fjord is an ~70 km long fjord stretching east from a skerry-guarded (skjærgård) region called Moraleda Channel (Spanish: Canal Moraleda), which is a body of water separating the Chonos Archipelago from the mainland of Chile. It is located at 45.26°S 73.00°W / -45.26; -73.00 and is connected indirectly to the open coast of the Pacific Ocean via the Darwin Channel. The Aisén river discharges at the head of Aysen Fjord.
Puerto Chacabuco is situated by the shores at the head of this fjord. Puerto Aisén lies on the Aisén River approximately 4 km above the head of Aysen Fjord. It serves as the capital for the Aisén Province.
The region is heavily influenced by a wide tidal reach (up to 8 meters). It lies near the West Wind Drift, a major oceanic surface current which encounters the west coast of Chile at 41° S latitude. The West Wind Drift splits into the northward flowing branch which meets the Humboldt Current and the southward flowing Cape Horn Current, providing ample heat to drive vaporization of the sea water, which results in onshore precipitation of 4,000 – 7,000 mm per year in the Chilean Andes. The moisture is driven onshore by prevailing westerly winds, the Roaring Forties.
Since January 2007 the fjord has suffered a series of minor earthquakes.