This lake has a length of 14.0 kilometres (8.7 mi) oriented to the northwest, a maximum width of 1.7 kilometres (1.1 mi) and an altitude of 411 metres (1,348 ft). This lake expands to 1.2 kilometres (0.75 mi) thanks to a bay facing east. This bay is the center of a semicircle of about 5.5 kilometres (3.4 mi) of radius on the east side of the lake, with a less rugged terrain whose highest hill reaches an altitude of 492 metres (1,614 ft). On the outskirts of this area, a series of mountains has several peaks, the highest reaching 699 metres (2,293 ft), or 7.3 kilometres (4.5 mi) of the lake. On the west side of the lake, the highest mountain peak is 625 metres (2,051 ft), which is 2.6 kilometres (1.6 mi) from the west shore of the lake.

The mouth of Lake Marquette is located at:

• 47.3 kilometres (29.4 mi) north-east of Gouin Reservoir;
• 28.0 kilometres (17.4 mi) south of the mouth of the Marquette River (confluence with the Ashuapmushuan River);
• 121 kilometres (75 mi) west of the mouth of the Ashuapmushuan River (confluence with lac Saint-Jean);
• 163 kilometres (101 mi) east of the mouth of lac Saint-Jean (confluence with the Saguenay River);
• 323 kilometres (201 mi) east of the mouth of the Saguenay River (confluence with the Estuary of Saint Lawrence).

The main hydrographic slopes near Lac Marquette are:

• North side: Marquette River, Normandin River;
• East side: La Tombelle Lake, Grand Portage River, Licorne River;
• South side: Loup River West, Berlinguet Creek;
• West side: Normandin River, Little Buade Lake, Buade Lake (Normandin River).

From the mouth of Marquette Lake, the current of the Marquette River flows over 64.9 kilometres (40.3 mi) generally to the north, to its mouth northwest of the Ashuapmushuan Lake. Then the current flows along the Ashuapmushuan River which flows over 193 kilometres (120 mi) to the northeast, then to the south-east to its confluence with the lac Saint-Jean where it empties on the West Bank at Saint-Félicien, Quebec.

• Saguenay River
• Lac Saint-Jean, a body of water
• Ashuapmushuan River, a watercourse
• Marquette River, a watercourse
• Le Domaine-du-Roy, a regional county municipality (MRC)
• Lac-Ashuapmushuan, Quebec, an unorganized territory
• List of lakes of Canada