Great Mountain Lake
46.158° N, 81.3588° W
Depth contours from the government survey. Not for navigation.
Download the depth map (SVG)Great Mountain Lake, Ontario. 46.158° N, 81.3588° W
Maximum depth 36.6 m. Scale bar on the map.
Not for navigation. Depths are from government surveys and may be outdated.
borealbound.ca/lakes/on/great-mountain-lake/, compiled October 9, 2026
- Canadian Geographical Names Database, Natural Resources Canada. Contains information licensed under the Open Government Licence – Canada.
- HydroLAKES v1.0, Messager et al. 2016 / WWF HydroSHEDS. Licensed under CC BY 4.0.
- Census boundaries and population, 2021, Statistics Canada. Adapted from Statistics Canada. This does not constitute an endorsement by Statistics Canada.
- Aquatic Resource Area survey points, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Fisheries Management Zones, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- Bathymetry lines and survey index, Ontario Ministry of Natural Resources. Contains information licensed under the Open Government Licence – Ontario.
- City page weather forecasts and alerts, Environment and Climate Change Canada. Contains data from Environment and Climate Change Canada (ECCC Data Servers End-use Licence).
- Air Quality Health Index observations and forecasts, Environment and Climate Change Canada. Contains data from Environment and Climate Change Canada (ECCC Data Servers End-use Licence).
- Guide to Eating Ontario Fish: Advisory Database, Ontario Ministry of the Environment, Conservation and Parks. Contains information licensed under the Open Government Licence – Ontario.
Great Mountain Lake is 36.6 m deep at its deepest point, deeper than 85% of the 2,688 surveyed lakes in Ontario. It covers 2.01 km² and lies 22 km southeast of Beaver Lake.
Government surveys have recorded 5 fish species here, including smallmouth bass, cisco and lake trout.
- Maximum depth
- 36.6 m
- deeper than 85% of the 2,688 surveyed lakes in Ontario
- Area
- 2.01 km²
- larger than 81% of the 18,731 lakes in Ontario
- Shoreline
- 16.4 km
- longer than 84% of the 18,731 lakes in Ontario
- Fish species
- 5
- more than 53% of the 2,454 surveyed lakes in Ontario
- Elevation
- 226 m
Today on the water
choppy Estimated waves, next 12 hours: up to 0.2 m. Around 11 a.m., wind from the northwest: the northwest shore is sheltered, waves build toward the southeast shore.
| Time | 10 a.m. | 1 p.m. | 4 p.m. | 7 p.m. | 10 p.m. | 1 a.m. | 4 a.m. | 7 a.m. |
|---|---|---|---|---|---|---|---|---|
| Wind km/h | NW 15 | NW 20 | NW 20 | NW 20 | var. 5 | SE 10 | SE 10 | SE 10 |
| Gusts km/h | 40 | 40 | 40 | |||||
| Waves (est.) m | 0.1 | 0.2 | 0.2 | 0.2 | ||||
| Temp. °C | 11 | 12 | 13 | 12 | 10 | 8 | 7 | 10 |
| Precip. % | 30 | 30 | 20 | 0 | 0 | 0 | 0 | 0 |
Today: Cloudy with 30 percent chance of showers this morning and early this afternoon then a mix of sun and cloud. Wind becoming northwest 20 km/h gusting to 40 late this morning. High 13. UV index 3 or moderate.
Weather: Killarney (local forecast), as of 9:05 a.m. EDT
Sun and moon
- Civil dawn
- 7:04 a.m.
- Sunrise
- 7:34 a.m.
- Sunset
- 6:50 p.m.
- Civil dusk
- 7:19 p.m.
- Moonrise
- 6:26 a.m.
- Moonset
- 6:08 p.m.
- Moon
- Waning crescent, 1% lit
Air Quality Health Index
2 low risk
Sudbury, as of 8:00 a.m. EDT
Depth
12% of Great Mountain Lake is deeper than 20 m.
How to read it: the lake’s area is sorted from the shore to the deepest point. Where the curve is flat, large areas share one depth (flats and weed beds); where it drops, depth changes quickly (drop-offs).
The government depth survey records a maximum depth of 36.6 m, drawn from 38 depth contours.
- Download the depth map (SVG)Printing this page gives the map on one sheet, with scale and sources.
Not for navigation. Depths are from government surveys and may be outdated.
Fish
Sport fish by the share of the 19 government surveys (2011–2011) that recorded them.
Eating your catch
The provincial guide to eating fish (2026) sets limits for 2 species from Great Mountain Lake. Maximum meals per month:
| Species | Length | General population | Sensitive population* | Contaminant |
|---|---|---|---|---|
| Lake Trout | 50-55 cm | 8 | 4 | Mercury |
| Smallmouth Bass | 35-40 cm | 8 | Do not eat | Mercury |
* As defined in the guide, including children and people who are or may become pregnant. Limits are for the length the guide lists most often; they change with the size of the fish. Read the official guide
Fishing regulations: Fisheries Management Zone 10. Check seasons and limits before you fish.