Surprise Lake has an area of 55 km and an indented perimeter exceeding 80 km. This body of water has the shape of a bird's head looking towards the East, with the beak open and raised towards the North-East; the bay collecting the waters of the stream of Evrey thus constitutes the neck of the bird.

This lake contains

• many islands including a main island of 6.5 kilometres (4.0 mi) in the center of the lake;
• several peninsulas including two (respective lengths of: 2.9 kilometres (1.8 mi) and 4.1 kilometres (2.5 mi)) attached to the east shore; the course of the [Roy River] flows westward between these two peninsulas;
• many bays, many of which are accessible by narrow passes including West Bay which collects the outlet of Phooey Lake, the South Bay which collects the waters of the [Yvonne River] and the bay of Evrey Creek (South side of the lake).

Neighboring South Caopatina Lake in which it flows by rapids, the Surprise Lake is located on the route of the Roy River, tributary of the Opawica River.

Surprise Lake gets its supplies on the east side by the Opawica River. "Surprise Lake" has a length of 15.4 kilometres (9.6 mi), a maximum width of 6.0 kilometres (3.7 mi) and an altitude of 343 metres (1,125 ft). Formed by a widening of the Opawica River, the "Surprise Lake" is rather deformed, with an archipelago of islands in the northwest, numerous bays and peninsulas.

This lake includes a peninsula attached to the north side of the lake and stretching on 4.1 kilometres (2.5 mi) to the southwest. The Opawica River crosses the northern part of this lake on 14.7 metres (48 ft) bypassing the latter peninsula by the south. Another peninsula attached to the eastern shore, i.e. south of the Opawica River, stretches over 5.7 kilometres (3.5 mi) towards southwestern of the lake, either in parallel to the current. An island of 3.1 kilometres (1.9 mi) is located in the southwestern part of the lake.

From the mouth of the lake, the current flows directly north to the confluence of the Irene River. This mouth of the "Surprise Lake" is located at:

• 5.9 kilometres (3.7 mi) south of the mouth of the Roy River;
• 12.5 kilometres (7.8 mi) south of the mouth of Caopatina Lake (which is crossed by the Opawica River);
• 28.0 kilometres (17.4 mi) Southeast of the mouth of Bras Lake Cut (Opawica River)) (which is crossed by the Opawica River);
• 100.6 kilometres (62.5 mi) east of the mouth of the Opawica River (confluence with the Chibougamau River);
• 430 kilometres (270 mi) south-east of the mouth of the Nottaway River;
• 55.6 kilometres (34.5 mi) northwest of a bay of Gouin Reservoir;
• 66.3 kilometres (41.2 mi) south of downtown Chibougamau;
• 53.9 kilometres (33.5 mi) south-east of the village center of Chapais, Quebec

The main hydrographic slopes near the "Surprise Lake" are:

• North side: Opawica River, Caopatina Lake, Des Vents Lake (Opawica River), Irene River, Eau Jaune Lake, Obatogamau Lakes;
• East side: Verviers Lake, Chrysologue Lake, Proust Lake, Oriol Lake, Verchères Lake, Opawica River, Gabriel Lake (Opawica River);
• South side: Roy River, Yvonne River, Pambrun Lake;
• West side: Aigle River (Doda Lake), Hébert River, Doda Lake, Opawica River.

• James Bay
• Nottaway River, a watercourse
• Matagami Lake, a body of water
• Waswanipi River, a watercourse
• Opawica River, a watercourse
• Doda Lake, a body of water
• Caopatina Lake, a body of water
• Roy River, a watercourse
• Yvonne River, a watercourse
• Eeyou Istchee Baie-James (municipality), a municipality
• List of lakes in Canada