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.

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.

Lake Muskoka Aerial Photography

Ontario photographs the province from the air on a rolling schedule.

The photograph below is from the SCOOP2023 collection, flown in 2023 and 2024.

Water quality

Ontario’s Lake Partner Program is a volunteer monitoring network. Participants collect a water sample each spring for phosphorus analysis and measure water clarity through the summer with a Secchi disk.

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 spring phosphorus. Below 10 micrograms per litre is oligotrophic: clear water and low algae. From 10 to 20 is mesotrophic: moderately productive water, with more algae and weed growth than an oligotrophic lake but rarely a bloom. Above 20 is eutrophic: nutrient-rich water, prone to algal blooms and low oxygen at depth.

A Secchi disk is a 20 centimeter 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.

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, sampled over 20 springs to 2025. Its long-term mean phosphorus concentration is 9.9 micrograms per litre, within the oligotrophic band, which extends to 10. The site’s 100 clarity readings give a median Secchi depth of 3.1 meters.

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 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.

Satellite thermal imagery gives a surface reading on clear days: the Landsat sensors pass over Lake Muskoka every eight days at a resolution of 100 meters. In the province’s record the surface reading and the one meter reading agree to within half a degree nine times in ten in summer.

The water a few meters down is colder than any figure on this chart, in every month of the year.

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.

Fish in Lake Muskoka

Ontario’s aquatic resource records name 33 fish species in Lake Muskoka. The province classes the lake as cold water. The record took effect on 21 December 2016, and its note records how the species present were confirmed: “for fish species confirmed by the Muskoka Lakes FAU, OMNR (1987-97), species that were only observed in angler caught lake trout stomach content samples (i.e. probably bait) and not indigenous to these lakes are excluded.” The province’s other records for the lake name two further species, rainbow trout and brook trout. They appear in the records below.

Thirteen of the 35 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 species, all of them mapped areas. One of the areas is one outline mapped for northern pike and largemouth bass alike. An outline filed for more than one species is drawn once, striped in each of their colours.

By number of records

By area mapped

• Smallmouth Bass49 areas23.2 ha
• Lake Trout37 areas6.7 ha
• Northern Pike22 areas24.4 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.

The province’s current stocking programme, recorded from 2016, lists 59,200 lake trout released into Lake Muskoka between 2016 and 2025.

Eating the fish

The 2025 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. The advice 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. Zone 15 covers central Ontario from Georgian Bay to the Ottawa River, bounded to the north by the Pickerel River, Highway 522 and the northern edge of Algonquin Park. It takes in Parry Sound, Huntsville, Bracebridge, Bancroft, Pembroke and Renfrew, and the whole of Algonquin Provincial Park. 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.

The figures are the number of fish an angler may catch and keep in a day and have in possession, under a sport fishing licence and under a conservation licence. The rows are the whole zone’s, and they apply to every lake in it. No waterbody exception names Lake Muskoka.

Lake Muskoka Ice Fishing

An ice hut on Lake Muskoka must be removed by March 31. Lake Muskoka lies in fisheries management zone 15, one of the twenty zones Ontario sets its fishing rules by, and one removal date applies across the whole zone.

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 zone 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.

When the ice goes out

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. It holds the day the ice left and carries no date for the day it formed, so it says nothing about when Lake Muskoka freezes.

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.

Getting on the water

Twenty-one access marks are mapped on Lake Muskoka: four boat launches, two enhanced shoreline access points, one shoreline access point, ten marinas, three beaches and one dam. Fifteen are Ontario’s own records and six are from the Overture Places dataset, and the list under the map says which is which. Boat launch is the province’s class for a ramp; enhanced shoreline access and shoreline access are its classes for a place the public can reach the water on foot.

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. The register records the origin of six names.

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

• Morrison Lake16 km away
• Three Mile Lake19 km away
• Lake Rosseau21 km away
• Six Mile Lake22 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, two enhanced shoreline access points, one shoreline access point, ten marinas, three beaches and one dam on Lake Muskoka.