Old Sow Whirlpool forming in Western Passage

Old Sow Whirlpool

Wirling vortex graphic
© 1997 Old Sow Publishing

What Is Old Sow?
Where Is It?
How Big Is Old Sow?
What Causes Old Sow?
Why Is It Called "Old Sow"?
Viewing Old Sow and Other Local Whirlpools
Other Tidal Oddities
Report Your Tidal Experience

A local legend tells of a fisherman in a dingy who found himself in the Old Sow maelstrom. His response...

“I didn't mind so much gettin’ caught in it. What I resented was havin’ to row uphill to get out!”

What Is Old Sow?

Old Sow is the largest natural whirlpool in the Western Hemisphere, and is one of five significant whirlpools worldwide. While most people envision a single, huge gyre when they think of a whirlpool, Old Sow infrequently and unpredictably — due, in part, to the nearby tidal dams that were built during the failed tidal power project of the 1930s — forms a large funnel in the water; however, it does frequently form a huge area of many kinds of facinating turbulence. The roiling comes in the forms of fast currents and eddies, standing walls of water, "boils," "spouts," "troughs" or "dishes," "holes," and numerous medium-size and small gyres. A rare major funnel is more apt to appear when tides are running especially high (as during spring tide), coinciding with strong winds.

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Where Is It?

Old Sow’s “sty” is Western Passage of Passamaquoddy Bay, in the Bay of Fundy. Western Passage is just west of Deer Island, New Brunswick, Canada, northeast of the island city of Eastport, Maine, USA, and east of Sipayik (Pleasant Point Passamaquoddy Reservation) and Perry on the Maine mainland. Western Passage connects the large open portion of Passamaquoddy Bay to its southern reaches.

Old Sow wanders around a bit, when active. On the flood tide, it occurs just to the west and north of the southern tip of Deer Island. It is near the international boundary, but is more on the New Brunswick side of the line. On the ebb tide, Old Sow wanders futher to the south, and is generally less apparent, although there is still considerable turbulence. Some mariners have reported that sometimes Old Sow is even more active on the outgoing tide.

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Just How Big Is Old Sow?

How does one measure a whirlpool? The broad area of disorderly water is vast, running from near Clam Cove, Deer Island, to south of the international bridge between Campobello Island, NB, and Lubec, ME, a distance of around 7 miles / 11 kilometres, and to the northeast, between Deer Island and Indian Island (just to the south of Deer Island); however, Old Sow itself — the largest vortex and its compatriots — is confined to an area that is much smaller.

In 1997 the Old Sow Whirlpool Survivor’s Association President took an aerial photograph of the whirlpool. Using the diameter of the navigation beacon tower at the southern end of Deer Island as a reference, he extrapolated that the smaller, but most active of the two large vortexes that were present at that time was approximately 76 metres / 250 feet in diameter!

For more technical information about Old Sow, visit our Data page.

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What Causes Old Sow?

Old Sow is tidal, and is the result of tremendous amounts of sea water rushing into a confined passageway (Western Passage of Passamaquoddy Bay), between Deer Island and Indian Island, then making a right-angle turn to the north around the southern tip of Deer Island, through a nearly 400-foot / 122-metre deep trench, around an underwater mountain that is around 119 feet / 36 metres below the water’s surface, and then into another trench of over 350 feet / 107 metres deep. Additional significant current comes from between Campobello Island and Indian Island, turning northward, and then joining the previously described current. Undersea ledges and tidal waters coming north via Friar Roads, between Campobello Island and Moose Island, Eastport, contribute to Old Sow’s activity. There are also countercurrents coming south from the St. Croix and the Magaguadavic Rivers through Passamaquoddy Bay. There are numerous currents and counter currents which affect the activity of Old Sow. Tidal surges that accompany storms, along with strong winds, can contribute to Old Sow’s activity.

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Why Is It Called "Old Sow"?

The name "Old Sow," some say, is due to a pig-like noise that the whirlpool makes when it is really churning. This explanation may be due to ancient folklore regarding "pigs of the sea" (porpoises), or may simply be a myth resulting from the whirlpool's current name. Old Sow does, however, make considerable noise when churning.

A more likely basis for the name, though, is corruption of the word "sough" (correctly pronounced "suff" or "so"), which has a couple of meanings: (1) a sucking noise, (2) a type of drain. Either of these definitions would apply to the whirlpool in question. People unfamiliar with the pronounciation of the written word "sough" might have assume that the pronunciation should be "sow," since the word’s ending is identical to many other words with an "ow"-sound ending, such as "plough" (pronounced "plow" and having the same meaning as "plow").

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Viewing Old Sow and Other Local Whirlpools

Boat charters and excursions based out of, Campobello Island, Deer Island, Eastport, and Lubec will sail through Old Sow, upon request. For those willing to take the risk (generally safe in a motor-powered boat operated by a qualified captian), the Old Sow Whirlpool Survivor’s Association makes Survival Certificates available to those who pass through the whirlpool and survive!

Old Sow area starts to roil about 3 hours before high water (high tide), and continues for a couple of hours. Even then, when activity has diminished considerably, strange troughs in the water are sometimes observed.

Deer Island

Moose Island (Eastport’s principle island)

East Coast Ferries, Ltd.

Many other small and medium size whirlpools, as well as other tidal oddities, can be seen in the area — Cobscook Reversing Falls at Pembroke’ Reversing Falls Park, under the Roosevelt Memorial International Bridge at the Campobello-Lubec border crossing, at the northern end of Indian Island (south of Deer Island; however, this whirlpool can be seen well only by boat or plane), and at various other locations in the Quoddy Loop area.

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Other Tidal Oddities

Other unusual tidal phenomena found in the area include thunder holes, tidal bores, reversing falls, inexplicable cross-currents, and standing waves. Even kelp passing edgewise over Cobscook Reversing Falls — with just a little imagination — can appear to be the finned spine of a seaserpent!

Thunder Holes

A thunder hole is an indentation (as in a crack or cave) in coastal rock that, when struck by a wave, makes a thunder-like noise. There are two or three thunder holes along the western portion of Quoddy Head State Park’s coastal trail in Lubec, another one south of there at Boot Head, and elsewhere in the area. Observing the “thunder” requires being present when the tide is at a height where waves strike the thunder hole in a certain way, rapidly compressing the air trapped within (similar to clapping cupped hands), thus producing the sound. Since the tides in the area range considerably at different stages of the moon, and occur at almost an hour later each day, being present at the right place and time may require serendipity. (The thunder hole at Green Point in Quoddy Head State Park has been observed approximately 1 hour 30 minutes after low water.)

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Tidal Bores

A tidal bore is a wall of water that arrives, under certain conditions, with the incoming tide. Like the great tides of the Bay of Fundy, it is caused by the geology of the sea bottom and shore becoming shallower and narrower, forcing the incoming volume of water to increase in speed. The water is forced against more stationary water or the ocean or river bottom ahead of it, causing it to rise up into a wall or wave. Local tidal bores have been occasionally observed east of Cobscook Reversing Falls in the western end of Cobscook Bay, between the southern end of Campobello Island and the Lubec mainland, and in the St. Croix River.

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Reversing Falls

This impossible-sounding phenomenon is caused by rocks situated in a narrow passage of tidal water where the volume and height of current reaching the passage is significant. When the tidal current strikes the rocks, it tumbles over them, and down the other side to a lower level of water. As the water on both sides of the rocks become equal, the ?falls? calms down, until at high or low water there are no falls at all. Then, the tide reverses, and eventually the difference in water level again becomes significant, forming a "falls" in the opposite direction. Since the tide reverses from high to low approximately every six hours, the falls also reverses at the same interval.

Note: The tide at Cobscook Reversing Falls occurs from 1 hour, 5 minutes to 1 hour, 15 minutes later than the tide in Eastport, depending on the direction of the tide. That in itself is unusual, in that — "as the crow flies" — the Falls are just six miles from Eastport, but tides at Reversing Falls occur over an hour later. (The area’s closest tide sensing station is located in Eastport, Maine, thus area tides in the US are calculated from this location. The closest Canadian tide sensing station is at Saint John, New Brunswick.)

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Standing Wall or Wave

A standing wave remains relatively stationary, and may be caused by colliding currents or by a current striking an underwater ledge. Such a wall can often be seen on the incoming mid-tide off the south end of Deer Island: a stationary wall of white water running from near the tip of the island off to the southwest.

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Report Your Tidal Experience

If you have information or have had an unusual encounter with a Quoddy-area tidal phenomemon that you'd like to share, please .

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Visit our sister website about
the Quoddy Loop.
Learn about the communities, businesses, and things to do and see
around Old Sow Whirlpool and Passamaquoddy Bay!


News, Feature Websites & Television Productions
about Old Sow:

October 20, 2014
The Weather Channel
Secrets of the Earth
Death Traps: Quicksand, Whirlpools & Riptides

The Death Traps "Whirlpools" segment is not online,
but periodically airs on The Weather Channel.

The History Channel

Underwater Universe: The Seven Deadly Seas
This program airs periodically on The History Channel.

October 2003
It'll Thrill Ya, It'll Kill Ya
about US-1 & Old Sow Whirlpool Survivors Association)

August 2001
Smithsonian Magazine
In the Eye of the Whirlpool

(about Whirlpools of the World, no longer online),
Close Encounters With the Old Sow,
written by the
Old Sow Whirlpool Survivors Association President.

Visit the Quoddy Loop
in the western Bay of Fundy of Maine and New Brunswick.
—A Three-Nation Vacation™—
© 2003–2020 Old Sow Publishing
PO Box 222, Moose Island
Eastport, Maine 04631
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Site updated 2015 June 17