Scottish Islands Explorer 40: Nov / Dec 2016

The Corryvreckan
The Corryvreckan
Gordon Eaglesham explains the whirlpool phenomenon
Between the islands of Jura and Scarba, lies a
mysterious maelstrom of sea water known as the
Corryvreckan. is natural phenomenon, the third
largest whirlpool in the world, is the result of powerful
Atlantic currents interacting with extraordinary
underwater topography which was the product of a
primeval catastrophe of enormous violence.
With a prodigious ridge extending 48 yards out of the
Camas nam Bairneach Bay by Scarba, it does not take
much of a westerly wind to set its cyclonic action in
motion - particularly during a spring tide. At this time,
the intense overfalls can be heard up to ten miles away,
with waves during storms approaching 30'.
Local fishermen refer to the tempestuous waters as the
Cailleach - a deity from Gaelic mythology that takes the
form of a hag. According to legend, she controls the
whirlpool, deciding which vessels will be claimed by its
abnormally strong currents and which will survive. Its
name derives from the Gaelic, Coire Bhreacian, meaning
‘cauldron of the speckled seas’.
Precise Timing
Crossing the Corryvreckan is possible during brief
periods of slack water, but requires precise timing. Boat
trips to the area are available from local harbours, and if
you are aer an aerial view, Oban Airport offers
sightseeing flights. e small port of Ardfern on the
banks of Loch Craignish as well as Easdale are the main
departure points.
During a spring tide, water is drawn up the Sound of
Jura and is then forced through a narrowing of the gulf
between Scarba and Jura, creating a bottleneck effect.
When combined with underwater features, including a
basalt pinnacle and an abyss descending 240 yards, along
with myriad undulations in the rock and seabed, vortices
of water develop.
The catalyst for this is usually an inundation of water
pouring into the cavernous hole and up to the base of
the pinnacle, where it meets the east face. Its epicentre
is directly above the pinnacle where the strongest
vortices are formed. With 33 yards between the top of
this geological oddity and the sea surface, it’s no wonder
that many have been caught off guard.
Most Challenging
e overfall during an ebb tide creates waterfalls on the
south side of the gulf as shallow waters meet greater
depths and the sea attempts to flatten itself out. It is
therefore unsurprising that the waters are regarded as
some of the most challenging in the world for diving. An
intricate tidal system exists between the islands and
mainland of the Argyll coast.
is creates anomalies which stretch the conventional
laws of physics. For example, as the main flood flows
north by the Mull of Kintyre, water is sucked out of the
Clyde Estuary. is causes an incredible peculiarity to
occur between Crinan and Lochgilphead, with a high
tide at one and a low tide at the other - despite only being
six miles apart.
Meanwhile far below the surface, the water is
vigorously stirred up by the unusual seabed. Countless
holes and undulations create intense tidal flows, eddies
and up-thrusts. The complex currents generated from
all this aquatic commotion can be observed on the
surface during calm conditions. It’s this unpredictability
that makes the Corryvreckan so notorious.
38 SCOTTISH ISLANDS EXPLORER NOVEMBER / DECEMBER 2016