Lake Ontario

Lake Ontario - Cruising & Navigation

St. Lawrence River to the Welland Canal

Lake Ontario is the easternmost of the five Great Lakes. Bordered on the north, west, and southwest by Canada and on the south and east by the State of New York. It is for the most part equally controlled by both Canada and the United States with the international boundary running approximately down the middle of the lake from the St. Lawrence River in the northeast to the Niagara River in the southwestern end of the lake.

Chart of Lake Ontario

The Lake is connected to the Atlantic Ocean via the St. Lawrence River. When proceeding upbound, the Niagara River and the Welland Canal is the connector to Lake Erie and the upper Great Lakes.

Additionally, The Trent-Severn Waterway in Canada, for pleasure boats, connects Lake Ontario at the Bay of Quinte to Georgian Bay (Lake Huron), via Lake Simcoe.

The Oswego Canal connects Lake Ontario at Oswego, NY to the New York State Canal System, with outlets to the Hudson River to the east, and Lake Erie to the west.

Lake Ontario is fed chiefly by the waters of Lake Erie by way of the Niagara River. This makes the Niagara River, located on the southwestern shore of the lake, the head of the lake. From the Niagara River, the lake water flows in a predominantly easterly direction to the mouth of the lake where it empties into the head of the St. Lawrence River in the far northeastern corner of the lake. The St. Lawrence River is the primary outlet for all five of the Great Lakes emptying into the Atlantic Ocean.

Lake Ontario Facts
Lake Ontario is the only one of the Great Lakes that does not border the state of Michigan.


Navigable access to Lake Ontario is limited to the Trent-Severn Waterway and the Welland Canal in Canada, the Oswego Canal in the USA, and the St. Lawrence River. The St. Lawrence River and the Welland Canal allow for deep draft vessels while the Oswego Canal and the Trent-Severn Waterway allow access only to shallow draft vessels.

Navigation Season

For all vessels the navigation season is governed by ice on the lake. For commercial vessels and lock operations, the navigation season begins in late March (20th to the 31st) and runs through late December (24th to the 31st). For most recreational boaters, they typically haul their vessels by mid-November and splash them again in May.

Because of its great depth, Lake Ontario never completely freezes over in winter. However, an ice sheet covering between 10% and 90% of the lake area typically develops. This being dependent on the severity of the winter. Ice sheets typically form along the shoreline and in well protected bays, where the lake waters are not deep.

Buoys and Marks

Buoys, beacons, and lights on Lake Ontario make use of the standard IALA Region B lateral buoyage system (Red Right Returning). Be aware of a buoyage system reversal at Lock O8 on the Oswego Canal in Oswego, NY.

Green Buoy Red Buoy

Buoy Guide

Lake Ontario Facts
Lake Ontario has a maximum length of 193 SM (168 NM / 311 KM) and a maximum width of 53 SM (46 NM / 85 KM).


NOAA Charts #14800, #14802, #14803, #14804, #14805, #14806, #14810, #14811, #14813, #14814, #14815, #14816, and #14822 provide full coverage of Lake Ontario’s U.S. waters from Clayton, NY on the St. Lawrence River to the Approaches to Port Weller, ON and the Welland Canal.

Chart #14800 – Provides limited detail for the entirety of Lake Ontario.

Chart #14802Clayton, NY to False Duck Island, ON (or south of Stony Point, NY) - Covers the eastern portion of Lake Ontario from Clayton, NY on the St. Lawrence River to False Duck Island, ON.

Chart #14803Six Miles South of Stoney Point to Port Bay - Covers the eastern portion of Lake Ontario from south of Stoney Point, NY to Port Bay, NY.

Chart #14804Port Bay to Long Pond - Covers the southern shoreline of Lake Ontario from Port Bay, NY to Long Pond, NY.

Chart #14805Long Pond to Thirty Mile Point - Covers the southern shore of Lake Ontario from Long Pond, NY to Thirty Mile Point, NY.

Chart #14806Thirty Mile Point, NY to Port Dalhousie, ON - Covers the southern shore of Lake Ontario from Thirty Mile Point, NY to Port Dalhousie, ON.

Chart #14810Olcott to Toronto - Covers the western end of Lake Ontario from Olcott, NY to Toronto, ON.

Chart #14811Chaumont, Henderson, and Black River Bays - Provides detailed coverage of the major bays along New York State’s eastern portion of Lake Ontario.

Chart #14813Oswego Harbor - Provides detailed coverage of Oswego, NY’s harbor.

Chart #14814Sodus Bay - Provides detailed coverage of Sodus Bay, NY.

Chart #14815Rochester Harbor - Provides detailed coverage of Rochester Harbor, NY.

Chart #14816Lower Niagara River - Provides detailed coverage of the Lower Niagara River to Horseshoe Falls between NY and ON.

Chart #14822Approaches to Niagara River and Welland Canal - Provides detailed coverage of the approaches to the Niagara River and the Welland Canal.

Canadian Hydrographic Service Charts provide coastal coverage from the Niagara River east to the St. Lawrence River along Canada’s portion of Lake Ontario.

Charts of Canadian waters are not available for viewing on line. However, the Canadian Chart Catalog does provide a general idea of the areas of coverage.

Listed below are Canadian Hydrographic Service Charts providing coastal coverage from the Niagara River east to the St. Lawrence River along the western and northern shore of Lake Ontario.

CHS Chart #2077 - Western Lake Ontario

CHS Chart #2086 - Toronto to Hamilton

CHS Chart #2058 - Cobourg to Oshawa

CHS Chart #2060 - Main Duck Isl. to Scotch Bonnet Isl.

CHS Chart #2059 - Scotch Bonnet Island to Cobourg

CHS Chart #2064 - Kingston to False Duck Islands

CHS Chart #1400 - Rockport to Lake Ontario

Many larger scale charts are available providing more detail of major harbors and constricted passages.

Charts (Electronic)

The following electronic charts provide detailed coverage of all the Great Lakes from Montreal, CA on the St. Lawrence River to Duluth, MN on Lake Superior including: Green Bay, Saginaw Bay, Georgian Bay, Lac Nipissing, Lake St. Clair, Lake Simcoe, Seneca Lake, Cayuga Lake, Oneida Lake, Trent-Severn Waterway, Thousand Islands, the St. Lawrence River from Kingston to Montreal, the Ottawa River from the St. Lawrence River to Ottawa, Mohawk River, Rideau River, Welland Canal and Erie Canal.


Digital - Bluechart G2 Vision microSD™/SD™ card: VUS042R-Great Lakes


C-Map Max Chart NA-M026: Great Lakes, North East Coast & Appr. – All of the Great Lakes


Navionics Platinum+ 901P+: East Great Lakes – Ontario, Erie, and Huron
Navionics Platinum+ 900P+: West Great Lakes – Huron, Michigan, and Superior


Other than in the area of Niagara Bar and Northeastern portions of the lake, keeping 1 NM offshore should provide you with good water and depths of 18 feet (3 Fathoms / 5.5 Meters) or greater.

Lake Ontario Facts
The Average depth of the lake is 283 feet (47 fathoms or 86 meters). The deepest point being 802 feet (133.7 fathoms or 244 meters) located at 43˚30.5’ N / 76˚ 58.0’ W. 13.76 NM (15.83 SM / 25.48 KM) North of Sodus Bay, NY.

Major Lights

Coast Lights with a range equal to or greater than 10 SM. From Tibbetts Point west along the south shore and north then east along the north shore of Lake Ontario:

Tibbetts Point Light
(Oc 10s 69ft 16 SM/13.9 NM/25.7 KM AIS)

Sodus Bay Breakwater Light
(Iso R 10s 51ft 10 SM/8.7 NM/16.1 KM)

Thirty Mile Point Light
(Fl 10s 60ft Priv)

Port Weller West Breakwater Light
(Iso R 4s 50ft 10 SM/8.7 NM/16.1 KM)

Hamilton Harbor Light
(Iso G 4s 14m 10 NM/11.5 SM/18.5 KM)

Point Petre Light
(Fl 10s 21m 11 SM/9.6 NM/17.7 KM)

Oswego Breakwater Light
(Fl R 10s 57ft 11 SM/9.6 NM/17.7 KM Horn)

Braddock Point Light
(Iso 6s 55ft 14 SM/12.2 NM/22.5 KM)

Fort Niagara Light
(Oc G 4s 80ft 10 SM/8.7 NM/16.1 KM)

Fifty Mile Point Light
(F G 11m 10NM/11.5 SM/18.5 KM)

Outer Harbor East Headland Light
(Fl R 10s 22m 13 NM/14.9 SM/24.1 KM)

Main Duck Island Light
(Fl 6s 24m 10 NM/11.5 SM/18.5 KM)

Distances and Mileages

Distances between major points on Lake Ontario are listed below. The distances table is useful in planning overnight stops while transiting the lake and is available for download.

Lake Ontario Distance Table (SM)
  Cape Vincent, NY Kingston, ON Oswego, NY Cobourg, ON Little Sodus Bay, NY Sodus Bay, NY Rochester, NY Toronto, ON Olcott, NY Hamilton, ON Niagara River Port Weller, ON
Cape Vincent,NY 0.0 24.0 49.0 101.0 59.0 69.0 89.0 160.0 134.0 186.0 154.0 160.0
Kingston,ON 24.0 0.0 55.0 101.0 64.0 72.0 90.0 160.0 134.0 185.0 154.0 159.0
Oswego,NY 49.0 55.0 0.0 91.0 15.0 29.0 59.0 145.0 113.0 166.0 133.0 141.0
Cobourg,ON 101.0 101.0 91.0 0.0 85.0 77.0 57.0 65.0 51.0 94.0 66.0 72.0
Little Sodus Bay,NY 59.0 64.0 15.0 85.0 0.0 18.0 48.0 136.0 104.0 157.0 124.0 131.0
Sodus Bay,NY 69.0 72.0 29.0 77.0 18.0 0.0 35.0 124.0 92.0 145.0 112.0 118.0
Rochester,NY 89.0 90.0 59.0 57.0 48.0 35.0 0.0 96.0 63.0 117.0 83.0 89.0
Toronto,ON 160.0 160.0 145.0 65.0 136.0 124.0 96.0 0.0 38.0 30.0 30.0 28.0
Olcott,NY 134.0 134.0 113.0 51.0 104.0 92.0 63.0 38.0 0.0 55.0 22.0 28.0
Hamilton,ON 186.0 185.0 166.0 94.0 157.0 145.0 117.0 30.0 55.0 0.0 39.0 30.0
Niagara River 154.0 154.0 133.0 66.0 124.0 112.0 83.0 30.0 22.0 39.0 0.0 11.0
Port Weller,ON 160.0 159.0 141.0 72.0 131.0 118.0 89.0 28.0 28.0 30.0 11.0 0.0
Distances shown above are in Statute Miles and are rounded to the nearest whole mile.

The above table can be downloaded for your personal and private use. The Lake Ontario distance file contains the tables in Statute Miles, Nautical Miles, and Kilometers. The files are Zipped Adobe (.pdf) format.

Lake Ontario Facts
Lake Ontario has a shoreline length of 634 SM’s (1,020 KM’s not counting any islands in the lake. When its islands are included, the lake's shoreline increases to 712 miles (1,146 km).

Speed Limits

The speed limits on the open waters of Lake Ontario can generally be considered to be unlimited except where posted or common sense prevails.

Transit Times

As a general guide, Cape Vincent, NY to the the Welland Canal could be done in a little over 4.5 hours at 30 knots.

More realistically, with a SOG of 15 knots you will probably require about 9.3 hours; 13.9 Hours at 10 knots, and 17.4 to 19.9 hours at typical trawler and sailboat speeds.

Tides and Currents


Studies show that the Great Lakes do in fact experience a semidiurnal tidal pattern. The tidal range however, is extremely small - averaging around 1 inch and reaching 1.6 to 2.0 inches (4-5cm) during the largest of tides. This tidal range is so small, that they are often hidden by other fluctuations in water levels that are caused by the weather. As a result, the Great Lakes are generally considered to be "non-tidal."

Water Level Fluctuations

The normal elevation of the lake's surface does in fact change. During the course of each year, Lake Ontario’s surface is subject to a consistent seasonal rise and fall, the lowest stages prevailing during the winter and the highest during the summer. These fluctuations generally average around 1.9 feet. Recently however it appears that lake levels are getting higher.

In addition to seasonal fluctuations, Seiche (changes in water level produced by winds, storms, squalls, and to a lesser degree, barometric pressure changes) often occur. These wind and barometric pressure changes that accompany squalls can produce fluctuations lasting from a few minutes to a few hours. Strong winds of sustained speed and direction can produce fluctuations lasting a few hours or a day. Lake Ontario has less of a problem with these water surface oscillations than the other Great Lakes due to the lake’s smaller surface area and depths. This effect is more pronounced in bays and at the extremities of the lake, where driven water is concentrated into a smaller area by converging shorelines.

Surface Currents

Lake Ontario’s main surface water current, often called a gyre, typically travels in a counter-clockwise direction around Lake Ontario. This is due to the Coriolis Effect caused by the Earth’s rotation.

Lake Ontario Surface Currents
(5cm/s is ≈ 0.1 knot)
Rarely do surface current speeds on Lake Ontario exceed 0.5 knot.

Keep in mind that these currents do not travel exclusively in one direction. There are frequent flow-reversals. Often the alongshore currents will be flowing west, and then reverse and flow east. These flow-reversals generally occur every 3-5 days in Lake Ontario. Wind direction shifts and wave action can also affect these surface currents.

Lake Ontario Facts
Lake Ontario has the smallest surface area of all the Great Lakes, (7,340 SM² / 18,960 KM²), yet is still ranked as the 13th largest lake in the world. With a fresh water volume of 393 SM³ (1,639 KM³), that works out to 432.7 Trillion (with a "T") gallons of water.


Like all of the individual Great Lakes, Lake Ontario acts like heat sink that moderates the temperatures of the surrounding land, cooling the summers and warming the winters. The lake also acts like giant humidifier, increasing the moisture content of the air. In the winter, this moisture contributes to the heavy snowfalls famous for this area and known as "Lake Effect" snow.


Typically winds on Lake Ontario are strongest in autumn with gales out of the southwest through northwest most likely occurring from October through December with winds.

Of particular concern is the eastern end of the lake. A funneling effect can occur with W and SW winds, which are prevalent throughout most of the year. As these winds encounter land, on either side of the eastern end of the lake they are accelerated. This can result in moderate winds in mid-lake often becoming dangerous gale force winds in this area.

Mexico Bay, located north of Oswego, NY is another problem area. Once known as "the graveyard of Lake Ontario" because of the large number of vessels foundering there in northwest through northeast winds.

In spring, northeasterly and easterly winds occasionally reach gale force throughout the lake. May through August is often the most settled weather; wind speeds of 15 knots or less are encountered 88.5% of the time.

Over the past 17 years, the strongest sustained measured wind on the lake was west-north-westerly at 50 knots occurring in November. Since extremes along the lake shore range from 50 to 65 knots, wind speeds mid-lake have the potential to reach 90 knots.


While visibilities are often restricted by any number of factors, fog is the most frequent and troublesome cause of reduced visibility on Lake Ontario.

Prolonged periods of rain and foggy weather are common when frontal systems moving into New York become stationary. During the spring, advection fog often reduces visibilities to below 0.5 mile up to 10% of the time. Being worst during the morning hours.

Along the shoreline, radiation fog is often found in fall under calm, clear nighttime skies. This fog occasionally drifts cut over the water typicaally burning off by noon. Visibilities of 2.5 miles or less occur about 10 to 13 days per month from October through March along the shore.


While rough seas can be encountered in any season, they are most often a problem during fall and winter. From October through February, wave heights of 5 feet or more can be expected between 10 and 20 percent of the time. Wave heights of 10 feet or more up to 2 percent of the time. Extreme wave heights of 17 to 19 feet have been encountered.

Since strong winds over a long fetch of water are conducive to creating rough seas, strong winds out of the E and W quadrants over Lake Ontario are often danger signals. Sea conditions are best from May through July when waves of less than 1 foot occurring 50% or more of the time.


While Thunderstorms can occur at any time, they predominantly occur during the summer months. Along the shorelines, they are recorded on 20 to 30 days a year with approximately 75 percent or more occuring between May and September.

They are most likely during late afternoons. Over the open lake, thunderstorms are most likely during August when they occur about 2 percent of the time. Summer thunderstorms are mostly night time events over the lake; most frequently between sunset and sunrise.


The main part of Lake Ontario usually remains open throughout the winter, with only a few patches of thin ice and slush during cold spells. During a normal winter, early ice cover appears toward the end of January and early decay begins in mid-March. During severe winters the significant ice is confined to the E end of the lake. E of Prince Edward Point, ice formation begins in early January. The area from Kingston to Prince Edward Point and Oswego is usually covered 70 to 90 percent with thin and medium lake ice by the end of the month. This thickness increases during February and reaches the thick category by early March. By this time, fast ice about 20 to 25 inches thick usually extends in an area from Prince Edward Point to Stony Point. Decay generally develops in early March, and by the third week most of the pack has melted off.

Meteorological Table – Lake Ontario
WX Element   May Jun Jul Aug Sep Oct   Annual
Wind > 33 Kts   0.2% 0.1% 0.1% 0.2% 0.4% 2.0%   1.2%
Seas > 9’   0.2% 0.1% 0.0% 0.1% 0.3% 1.4%   0.7%
Visibility < 2 NM   11.3% 13.0% 6.9% 5.6% 5.5% 4.0%   7.6%
Precipitation   8.8% 6.8% 5.2% 5.9% 9.3% 11.0%   10.2%
Temps > 69° F   1.5% 8.7% 41.7% 47.1% 12.9% 0.6%   12.7%
Mean Temps °F   49.8° 60.1° 69.3° 69.7° 62.7° 52.1°   54.0°
Temps < 33° F   0.2% 0.0% 0.0% 0.0% 0.1% 0.5%   5.9%
Wind Direction   W SW SW SW SW W   W
Thunderstorms   1.0% 1.8% 2.0% 2.0% 1.4% 0.8%   1.2%
Wind Speeds ≤ 15 Knots   84.8% 89.0% 90.3% 89.8% 83.7% 77.1%    
Wind Speeds ≤ 10 Knots   64.0% 68.3% 70.5% 71.8% 66.4% 56.8%    

Weather Radio

U.S. - NOAA Weather Radio

National Weather Service (NOAA Weather Radio) - Stations provide mariners with VHF-FM broadcasts of weather warnings, forecasts, radar reports and surface weather observations. Reception range is up to 40 miles from the antenna site, depending on the terrain, type of receiver and antenna used.

Lake Ontario - NOAA Weather Radio
Call Sign Station Frequency Channel
WXN-68 Watertown, NY 162.475 MHz WX-3
WXL-31 Syracuse, NY 162.550 MHz WX-1
KHA-53 Rochester, NY 162.400 MHz WX-2
KEB-98 Buffalo, NY 162.550 MHz WX-1

Canadian Weather Radio (Environment Canada)

Environment Canada (Canada Weather Radio) - Stations provide mariners with basically the same type weather information as their counterpart; NOAA Weather Radio and making use of the same frequencies. VHF-FM broadcasts of weather warnings, forecasts, radar reports and surface weather observations. Reception range is up to 60 kilometers from the antenna site, depending on the terrain, type of receiver and antenna used.

Lake Ontario - Canadian Weather Radio
Call Sign Station Frequency Channel
  Kingston, ON 162.400 MHz WX-2
  Belleville, ON 162.425 MHz WX-4
  Toronto, ON 162.400 MHz WX-2
  St. Catharines, ON 162.475 MHz WX-3
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