Lake Muskoka

Where Lake Muskoka is

Lake Muskoka lies in the District Municipality of Muskoka, with shoreline in the Town of Gravenhurst, the Town of Bracebridge and the Township of Muskoka Lakes.

How deep is Lake Muskoka?

Lake Muskoka reaches a maximum recorded depth of 73.1 meters, determined from 365,520 soundings taken during Ontario’s 2000 survey.

See also Ontario's Largest and Deepest Lakes

Surveyed Depths

Ontario has surveyed the depths of several thousand of its lakes over more than half a century. Later surveys were conducted by boat with satellite positioning and produced hundreds of thousands of soundings per lake. Earlier surveys were charted by running transects across the water and drawing depth contours by hand.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect water samples for phosphorus analysis and measure water clarity through the summer with a Secchi disk. Most sites are sampled for phosphorus once a year, in spring, and some several times a year between spring and fall. Phosphorus in many lakes rises through the summer, so the two kinds of average are measured on different bases.

Phosphorus is the nutrient that controls how much algae a lake can grow. A lake with little phosphorus stays clear and supports cold-water fish such as lake trout. As phosphorus rises, algae increase, the water clouds, and oxygen in the deep water falls as the algae decay. The province classifies each monitoring site by its average phosphorus:

• Oligotrophic, below 10 micrograms per litre: clear water and low algae.
• Mesotrophic, from 10 to 20: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom.
• Eutrophic, above 20: nutrient-rich water, prone to algal blooms and low oxygen at depth.

Lake Muskoka has 21 Lake Partner monitoring sites. Nine have reported phosphorus for the three or more years the province requires before a status is assigned. Eight of those sites are classified oligotrophic and one mesotrophic.

The longest record is held by site 2465/17 at MuskokaBay-Greavette, with phosphorus sampled once a year over 20 years to 2025. Its long-term mean phosphorus concentration is 9.9 micrograms per litre, within the oligotrophic band, which extends to 10.

A Secchi disk is a white or black-and-white plate lowered on a marked line until it disappears from view. The depth at which it vanishes is the Secchi depth, a direct measure of water clarity. Clearer water gives a deeper reading.

The 100 clarity readings at site 2465/17 give a median Secchi depth of 3.1 meters.

Median Secchi depth by year at site 2465/17

See also Lake Water Quality and Blue-Green Algae in Ontario

Lake Muskoka Weather

The weather page for Lake Muskoka carries the forecast over the water, wave heights across the lake, the modelled water temperature, and the water level.

Lake Muskoka weather

Water temperature

Ontario’s aquatic resource records class Lake Muskoka as a cold-water lake, with a mean depth of 15 meters against its maximum of 73.1.

A deep lake separates into layers through the summer. Sunlight and wind warm and mix the upper few meters, and beneath a band of rapid cooling, the thermocline, the water stays cold through the whole season. A mean depth of 15 meters places most of Lake Muskoka’s volume in that cold layer, which is the condition lake trout and lake whitefish require.

No provincial monitoring station records water temperature on Lake Muskoka. The weather page for Lake Muskoka carries the LastLake model’s surface water temperature for each day of the coming week. The province’s longest in-water record is kept on eight research lakes near Dorset, sampled since 1976. A reading is taken at the surface, at one meter, at each meter to seven and then every two meters to the bottom, about every two weeks through the open-water season and about monthly under ice. The record holds 5,240 readings at a depth of one meter.

At one meter the eight lakes track one another closely. On a day when several were sampled, the warmest and the coolest lake differed by about one degree in every month of the year, and a 12 meter deep lake and a 37 meter deep lake read within 0.2 degrees of each other from June to October. The weather of the year, and not the lake, sets most of the width of the band below.

Water temperature at a depth of one meter (eight lakes near Dorset, ON)

How depth changes the temperature

The chart below is the province’s record on Harp Lake, 37 meters deep, drawn as the median temperature at each depth for each month over 49 years. In July the water at one meter is 23 degrees, at five meters 15, at seven meters 9, and from 13 meters to the bottom under 6. By October the warm layer has deepened to seven meters and cooled to 11 degrees. In February the whole column sits between 1 and 4 degrees under the ice, coldest at the top.

A shallower lake in the same record warms sooner. Heney Lake, six meters deep, reads about 1.8 degrees warmer than Harp Lake at one meter from January to May, 0.8 degrees warmer from June to August, and the same or cooler from September.

See also Lake Water Temperature in Ontario

Fish in Lake Muskoka

Ontario’s aquatic resource records name 33 fish species in Lake Muskoka. The province’s other records for the lake name two further species, rainbow trout and brook trout. They appear in the records below.

Popular species in the province’s records

• Lake Trouttrout and whitefish
• Lake Whitefishtrout and whitefish
• Ciscotrout and whitefish
• Northern Pikepike
• Walleyeperch
• Yellow Perchperch
• Smallmouth Basssunfish
• Largemouth Basssunfish
• Black Crappiesunfish
• Rock Basssunfish
• Pumpkinseedsunfish
• Burbotcod
• Brown Bullheadcatfish

Spawning areas

Ontario maps 113 fish spawning records within the Lake Muskoka outline, for six different species, and all of them are mapped below.

By number of records

By area mapped

• Smallmouth Bass49 areas23.2 ha
• Lake Trout37 areas6.0 ha
• Northern Pike22 areas24.3 ha
• Rainbow Smelt2 areas900 m²
• Largemouth Bass2 areas5.1 ha
• Walleye1 area600 m²

The federal Fisheries Act prohibits the harmful alteration, disruption or destruction of fish habitat without an authorization, so a dock, dredging, infill or shoreline work at a mapped spawning area is reviewed on that basis.

Stocking history

Ontario’s stocking records for Lake Muskoka run from 1946 to 2015 and hold 118 releases. Walleye account for most of the fish: 5,027,100 released in seven of the years between 1946 and 1989. The last recorded release was 3,500 lake trout yearlings in 2015.

Eating the fish

The 2026 Guide to Eating Ontario Fish carries consumption advice for ten species taken from Lake Muskoka, tested for contaminants at a sampling location in Gravenhurst Bay, Muskoka Twp. Each figure below is the most meals a month the guide advises for a fish of that length. Where mercury sets the advice, the figure falls as the fish gets longer, because mercury accumulates over a fish’s life. A zero means the guide advises no meals of that fish at that size.

General population: adultsSensitive population: children under fifteen, women who are or may become pregnant

Fisheries Management Zone 15

Lake Muskoka lies in Fisheries Management Zone 15. Ontario sets its fishing seasons and catch limits by zone. The province describes it as a zone of many natural lake trout and brook trout lakes, with a well-developed road network and moderate angling effort.

Fisheries management zones around Lake Muskoka

See also Fishing Seasons in Ontario, Zone by Zone and Fish Stocking in Ontario Lakes

Lake Muskoka Ice Fishing

An ice hut on Lake Muskoka must be removed by March 31. The province sets dates for ice hut removal as a safety measure to ensure huts are removed before thawing occurs. One date applies to an entire fisheries management zone (FMZ). Lake Muskoka lies within FMZ 15.

An ice hut must also be removed before the ice breaks up, whether or not that date has passed. The deadline clears huts from the ice ahead of the thaw and does not close the fishing season.

Registration is required in FMZ 15 for an ice hut built of anything other than fabric, and for a fabric tent covering seven square meters or more. Registration is free, and the number is displayed on the outside of the hut.

Ice Out Date

The ice has been recorded leaving Lake Muskoka in 94 springs between 1900 and 1993. The median date is April 21. The earliest recorded break-up is March 31 in 1946, and the latest is May 12 in 1926.

Across the 94 recorded springs the median date has moved by less than a day each decade.

The record was contributed by Peter J. Dillon, Ontario Ministry of the Environment to the Global Lake and River Ice Phenology Database. The record only holds the ice-out dates for Lake Muskoka, and no ice-in date.

Ice out dates for 94 recorded springs between 1900 and 1993

Ice conditions

No public record reports the thickness or the condition of the ice on Lake Muskoka on any given day. Ontario publishes ice safety guidance for anyone going out on the ice, at ontario.ca.

See also Lake Ice in Ontario and When the Lakes Will Freeze This Winter

Getting on the water

Twenty-one access marks are mapped on Lake Muskoka.

See also Boat Launches on Ontario Lakes

Islands and names

Lake Muskoka contains 220 islands in the Ontario Hydro Network’s outline, seventeen of them over 10 hectares and 42 under a tenth of a hectare.

Official names

Ontario’s geographic names register lists 258 official names on the water and its islands: 186 islands, 43 bays, one shoal, five rocks, one cut, six narrows, seven points on islands and one river. A further 43 named points stand on the mainland shore.

Bays 43

• Archer's Bay
• Babies Bay
• Bala Bay
• Bear Bay
• Boyd Bay
• Broadley Bay
• Brydon Bay
• Buttler Bay
• Cleaver Bay
• Cliff Bay
• Dark Bay
• Dudley Bay
• East Bay
• Ennis Bay
• Goodwill Bay
• Jeanneret Bay
• Long Bay
• Luna Bay
• Milford Bay
• Minnow Bay
• Mounts Bay
• Muskoka Bay
• Neilson Bay
• North Bay
• Packers Bay
• Portage Bay
• Sandy Bay
• Scarcliffe Bay
• Shadow Bay
• Shanty Bay
• Skinner Bay
• South Bay
• Stephens Bay
• Strawberry Bay
• Sugarbush Bay
• Sunny Bay
• Sunset Bay
• Sunset Bay
• Sutherland Bay
• Suttaby Bay
• Torrance Bay
• Walkers Bay
• Whiteside Bay

Shoals and rocks 6

• Big Ben Rock
• Freds Rock
• Gull Rock
• Jibilto Shoal
• Pudding Rock
• Snub Rock

Harbours, cuts and narrows 7

• Coulter Narrows
• Fenns Narrows
• Jannacks Narrows
• Kemp Narrows
• Lighthouse Narrows
• Lowes Narrows
• The Cut

Points on the shore 43

• Adam Point
• Black Point
• Breezy Point
• Broadley Point
• Christenson Point
• Cooper Point
• Dudley Point
• Fenns Point
• Greenwood Point
• Halls Point
• Hanna Point
• Hemlock Point
• Hialeah Point
• Hudsons Point
• Hutton Point
• Kareen Point
• Kennedy Point
• Lady Point
• MacIvers Point
• Montcalm Point
• Mortimers Point
• Pages Point
• Parkers Point
• Petes Point
• Pine Needle Point
• Pine Point
• Pleasant View Point
• Point Kaye
• Point Manchee
• Point William
• Poplar Point
• Red Secret Point
• Robbys Point
• Rookery Point
• Sandy Point
• Scarcliffe Point
• Shantyman Point
• Snubbin Point
• Strawberry Point
• Struan Point
• Sutton Point
• View Point
• Walkers Point

Communities on the lake 7

• Bala
• Torrance
• Milford Bay
• Beaumaris
• Walkers Point
• Mortimers Point
• Gravenhurst

Nearby lakes

• Butterfly Lake14 km away
• Morrison Lake16 km away
• Three Mile Lake19 km away
• Tea Lake19 km away

All lakes

Questions about Lake Muskoka

• How deep is Lake Muskoka?

  Its maximum recorded depth is 73.1 meters, determined during Ontario’s 2000 survey.

• How big is Lake Muskoka?

  Its surface covers 119.9 square kilometers and it holds 220 islands. Of its 451 kilometers of shoreline, 261 kilometers is the mainland shore and 190 kilometers is the shore of the islands.

• What fish are in Lake Muskoka?

  Ontario’s aquatic resource records name 33 species, among them lake trout, walleye, smallmouth bass, largemouth bass, northern pike and lake whitefish. The lake’s spawning, consumption and stocking records also name rainbow trout and brook trout.

• Is there a public boat launch?

  Records mark four boat launches.