England Ireland Find Havens
England Ireland Find Routes


Navigating Blasket Sound

Tides and tools

Be the first
to comment

What is the route?
This is the shortcut around the Dingle Peninsula taking a cut inside the Blasket Island Group. The route utilises Blasket Sound which occupies the space that lies between the northeastern end of Great Blasket Island and the mainland shore.

Why sail this route?
Blasket Sound is a very attractive option for a leisure craft passing north or south along this coastline as it cuts at least 20 miles off any passages between Valentia and the River Shannon. It is also very easily navigated being, at its narrowest point, ½ mile wide and having the benefit of a natural leading line on the mainland’s coastal features. This makes daylight pilotage through the sounds fairway very straightforward and it provides a convenient route that avoids the extensive rocks and shoals that lie to the west of Great Blasket.

Blasket Sound as seen from the Dingle Penninsula
Image: Tourism Ireland

As such, in reasonable weather, with fair wind or tide, Blasket Sound is the preferred leisure boat passage. But, in unsettled weather or at night, with its exposed position, uneven bottom and strong tides, it is best to pass to the seaward of the island group and its dangers.

The southern approach to Blasket Sound
Image: Chris Brooks via CC BY-SA 2.0

Likewise, its tidal streams can be confused and unpredictable at times so a vessel taking this route should be able to avail of a reliable engine.

Tidal overview
Today's summary tidal overview for this route as of Sunday, April 21st at 21:17. The speed of the tidal streams in the main channels varies but is generally about 1 to 3 kn that can cause occasional overfalls and eddies. As such it is advisable to make a transit with a favourable tide or at least before it reaches its maximum rate.

Tides in the Blasket Sound turn in line with the channels. The flood streams northward commencing at HW Dover -0120 (Cobh +0430), and ebb streams southward commencing at HW Dover +0440 (Cobh -0035). The tide turns approximately half an hour ahead of the local HW and LW which is approximately Cobh -0110. Sustained southerlies make the flood run for longer and stronger.

South Going Stream

(HW Dover +0430 to -0130)


(Tidal flow )

Ends in 00:37:54

(Sun 15:30 to 21:55)

North Going Stream

(HW Dover -0120 to +0440)

Starts in 00:31:53

(Sun 21:49 to 03:49)

What are the navigational notes?
Please use our integrated Navionics chart to appraise the route. Navionics charts feature in premier plotters from B&G, Raymarine, Magellan and are also available on tablets. Clicking the 'Expand to Fullscreen' icon opens a larger viewing area in a new tab.

Expand to
new tab or fullscreen
Please zoom out (-) if all of the waypoints are not displayed.
The above plots are not precise and are indicative only.


Great Blasket Island as seen from the northeast
Image: Maciej Brencz via CC BY 4.0

Three miles long, less than ½ a mile wide, and lying in a northeast direction, Great Blasket Island is the largest of the Blasket group. It is situated a mile to the west of Dunmore Head which is the nearest point of the mainland. The island rises from a narrow base to the height of 289 metres at its highest point, at 'An Cró Mór', and is very steep presenting a wall of vertical cliffs along its northwest side. It can be further identified by the ruined Eask Tower on the summit of a 229 metres high ridge 1½ miles northeastward of the summit of 'An Cró Mór'.

Dunmore Head
Image: Tourism Ireland

Blasket Sound lies between the north-eastern end of Great Blasket Island, the dangers to the north of it, and the mainland to the east. The sound’s narrowest part resides between the easternmost extremity of Great Blasket Island, called Garraun Point, and the mainland’s Dunmore Head.

Blasket Sound as seen from Great Blasket Island
Image: Janek Kloss

The channel is then reduced to less than ¾ of a mile in width by a remarkable narrow strip of rock that extends from Dunmore Head to terminate on its western side by a 44 metres high conical rock called the Lure. From a short distance, this strip of rock appears as an island.

The Lure extending from Dunmore Head with Great Blasket in the backdrop
Image: Tourism Ireland

Beyond The Lure and Garraun Point, almost half of the distance across from the former, is a series of several dangerous covered and drying rocks. The drying rock, called Scollage Rock, lies 150 metres out from the Lure’s extremity. It is covered at high water and dries to 3.7 metres.

The Lure as seen from the sound with Scollage Rock just breaking (far right)
Image: Burke Corbett

The Stromboli Rocks lie in the channel about six hundred metres west-southwest of Scollage Rock and consist of several small pinnacles with a least depth of 1.8 metres over them. These all break heavily in bad weather and reduce the fairway to a width of ½ a mile on the western or island side.

The Lure as seen from Blasket Sound
Image: Tourism Ireland


The complete course is 7.89 miles from the waypoint 'Southern Approach to Blasket Sound' to '½ a mile west of Sybil Points outliers' tending in a northerly direction (reciprocal southerly).

Southern Approach to Blasket Sound, 52° 2.916' N, 010° 31.527' W
This is on the alignment of the sharp pointed Clogher Rock, on 015° T with the ruins of the tower, or the summit on which it stands, that leads clear of the dangers in the sound.

       Next waypoint: 3.44 miles, course 15.36°T (reciprocal 195.36°T)

Middle Blasket Sound waypoint, 52° 6.234' N, 010° 30.043' W
Safe mid-point fix to Blasket Sound passage

       Next waypoint: 1.51 miles, course 15.34°T (reciprocal 195.34°T)

Northern Approach to Blasket Sound, 52° 7.689' N, 010° 29.393' W
This is the point where a southbound vessel picks up the alignment, or a northbound vessel breaks off transit to clear Sybil Point’s outliers.

       Next waypoint: 2.94 miles, course 355.28°T (reciprocal 175.28°T)

½ a mile west of Sybil Points outliers, 52° 10.614' N, 010° 29.787' W
This is ½ a mile west the Maher-aneig rocks off Sybil Point.


Navigation through Blasket Sound revolves around making a passage of about 5 miles on the alignment of 015° T (or 195° T southbound) of:

  • • The old tower on the summit of Sybil Point situated 4½ miles northward of the narrows.

  • • Clogher Rock lying close off Clogher Head, 2 miles southwestward of Sybil Point.

Sybil Point terminates in a bold precipice which rises to a height of 206 metres. The tower may not be easily identified from the south, but the summit on which it stands is easily picked out to provide the leading mark.

Sybil Point as seen from the south with the hump and tower on top (top right)
Image: Tourism Ireland

The rugged 113 metres high Clogher Head lies about 1.7 miles south of Sybil Point. It has the prominent and sharply pointed above-water Clogher Rock close off the head.

Bringing Clogher rock into line with the tower from the north
Photo: Graham Rabbits

These, in line 015° T / 195° T, lead through the centre of the narrows and then a ¼ of a mile east of Beginish Island and its surrounding dangers.

On transit as seen from the south
Image: Burke Corbett

From the south, keep centre alignment at all times particularly at the narrowest point of the sound, between Great Blasket Island’s Garraun Point and Dunmore Head where the fairway reduces to ½ a mile.

The northern side of Blasket Sound
Image: d_marino2001 via CC BY 2.0

Once past the narrows, the passage becomes partially sheltered by a large number of rocks and islets that extend a mile northward from Great Blasket making for a much more comfortable run.

In the area between Blasket Sound and Sybil Point, there can be a nasty race in west or northwest winds over the north-going tide. In fine weather, in the absence of a heavy swell, this presents no problem.

At the 'Northern Approach to Blasket Sound' waypoint, the vessel is abeam of the north ends of the group's Connor Rock, about a mile to the west, with open sea ahead. From here it is time to depart the transit and continue northward to clear the Maher-aneig rocks that extend a ⅓ of a mile off the steep cliffs of Sybil Point. Southbound vessels should just apply the reverse.

Vessels should be prepared for sudden and violent gusts of the wind, that comes off the mountains and high islands in this area.

An Trá Ban clearly visible as a low cloud hangs over Great Blasket Island
Image: Tourism Ireland

Those with a little time to spare may take the opportunity to visit Great Blasket Click to view haven. Close northwest of Garraun Point and upon the shore facing the mainland, there is a beach called An Trá Ban. In fine weather, a vessel may anchor off the beach in 3 metres over a sandy bottom and land on the beach or at the island slip close southeast of the beach.

An Trá Ban anchorage overlooked by the ruins of the old settlement
Image: Tourism Ireland

What is the best sailing time?
Sailing season for Ireland is May to September, with June and July offering some of the best weather. Nevertheless the incidence of winds up to force seven and above in June and July are on average two days each month. So you may be either held up or having a blast depending on your sailing preferences. Ireland is not subject to persistent fog – statistically complete days of persistent fog occur less than once in a decade.

Are there any security concerns?
Never an issue known to have occurred to a pleasure vessel sailing off the Irish coast.

With thanks to:
eOceanic and Burke Corbett, Gusserane, New Ross, Co. Wexford.

Expand to
new tab or fullscreen

Views of Great Blasket

A photograph is worth a thousand words. We are always looking for bright sunny photographs that show this route and its identifiable features at its best. If you have some images that we could use please upload them here. All we need to know is how you would like to be credited for your work and a brief description of the image if it is not readily apparent. If you would like us to add a hyperlink from the image that goes back to your site please include the desired link and we will be delighted to that for you.

Add your review or comment:

Please log in to leave a review of this route.

Please note eOceanic makes no guarantee of the validity of this information, we have not sailed this route and do not have first-hand experience to qualify the data. Although the contributors are vetted by peer review as practised authorities, they are in no way, whatsoever, responsible for the accuracy of their contributions. It is essential that you thoroughly check the accuracy and suitability for your vessel of any waypoints offered in any context plus the precision of your GPS. Any data provided on this page is entirely used at your own risk and you must read our legal page if you view data on this site.