Dark waters enclosed within dizzying cliffs give the Saguenay Fjord a somewhat mysterious aspect. The Fjord is at once a sea and a river, as cold salt water from the St. Lawrence estuary invades its depths, while warmer fresh waters from its tributaries and Lake St. Jean run along the surface. This sector is a favourite of recreational boaters and fishing enthusiasts.

It covers 17 % of the park. Classified among the longest fjords in the world, the Saguenay Fjord is over 105 km long. It is made up of three basins defined by sills, including one shallow (20 m) sill 7 km from the mouth of the river. When the tide comes in, the Saguenay receives a wealth of nutrients from the lower estuary, carried by the cold salty oxygen-rich water carrying plankton that breathes life into the deepest depths of the fjord.

it extends to

• Dug by the passing of glaciers thousands of years ago
• One of the rare fjords that release its waters to an estuary and not an ocean
• A deep valley (about 275 m), lined with high cliffs, ends with a shallow sill (about 20 m)
• Ranked as one of the world’s longest fjords, it extends to 105 km
• It the limits of the park, the shores are protected by the parc national du Fjord-du-Saguenay, a provincial park.