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Dalkey Sound Cut - Dublin to Killiney Bay

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What is the route?
Dalkey Sound lies between the small the mainland eastern extremity of Sorrento Point and Dalkey Island that forms the south-eastern extremity of the bay of Dublin. As the shore of the mainland is
steep-to and Dalkey Sound cuts about a mile off a passage between Killiney and Dublin bays, it is the normal approach used by inshore leisure craft. The sequence of description is south to north but it may be used either way with favourable tides.

Dalkey Sound as seen from the mainland side
Image: Michael Harpur

Why sail this route?
There are three main ways enter the southern side to of Dublin Bay, or for a southbound vessel to connect with the inshore passage which is the preferred route as far as Wicklow.

  • (i) Pass between Dalkey Island and the mainland via Dalkey Sound.

  • (ii) Pass between Dalkey Island and the Muglins via Muglins Sound.

  • (iii) Pass outside the Muglins, offshore and in openwater.

Dalkey Island and The Muglins as seen from the south
Photo: jnestorius cc BY-SA 3.0

The Muglins Sound Route location, option (ii), has the complication of the foul ground that lies to the northward of Dalkey Island, in particular, the scarcely awash and unmarked Leac Buidhe Rock situated about 200 metres east of Clare Rock. However, in the case of an adverse tide, a vessel of moderate speed is better off to opt for Muglins Sound or to pass further offshore to avoide the natural funnel effect in Dalkey Sound where the strongest streams will be encountered.

The much more straightforward offshore route, option (iii) detailed in the Dublin Bay to Rosslare Route location Coastal Description, would be the best approach for a newcomer to take at night, with poor visibility or in uncomfortable weather, but it adds miles.

Southbound yacht in Dalkey Sound
Image: CC0

This Dalkey Sound, option (i), although a narrowish channel that has unmarked dangers on either side, it is ample wide for leisure vessels to freely sail through and it presents a clear passage with a least depth of 8-metres through the fairway. It is also the shortest cut and all that is required is to simply keep about 100 metres off the steep-to mainland shoreline to traverse the Sound. All of these reasons make this the normal route for leisure craft passing along the coast.

Northbound boat passing through Dalkey Sound
Image: Michael Harpur

Favourable tides, however, are critical to pass through Dalkey Sound. Dalkey Sound streams can attain up to 2.5 knots and it is only when these are adverse that leisure craft are best advised to take one of the other two options.

Tidal overview
Today's summary tidal overview for this route as of Wednesday, April 17th at 13:44. In Dalkey Sound and the south part of Dublin Bay the tide turns about half an hour earlier than it does offshore. The northwest going stream begins at Dover -0600 (HW Dublin +0555). The southwest going stream begins at Dover HW (HW Dublin -0030).


(HW Dover +0000 to +0612)

Starts in 05:36:16

(Wed 19:21 to 01:33)


(HW Dover -0600 to +0000)


(Tidal flow )

Ends in 05:36:16

(Wed 13:21 to 19:21)

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.

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The above plots are not precise and are indicative only.


Dalkey Island resides off Sorrento Point, the southern entrance to Dublin Bay and lies about 2½ miles southeast of Dún Laoghaire Harbour. The small island is 24 metres high and 600 metres long with a Martello tower on its summit. It lies immediately offshore 300 metres to the east of the mainland leading down to Sorrento Point. The shore of the mainland is steep-to, but the reef that extends up to about ½ a mile north-northwest of the island, terminating in Maiden Rock, has straggling outliers on both sides.

Sorrento Point and Dalkey Island as seen from Killiney Hill
Image: Passps via ASA 4.0

Dalkey Sound leads between the island and the mainland and it has from 6.8 to 12.6 metres LAT of water. The mainland shore is steep-to and vlean, but the reef that extends northward from the island, terminating in Maiden Rock, has straggling outliers on both sides of it. When using the Sound keep a central route if slightly towards the the mainland rather than Dalkey Island circa 100 metres or so.

The key determinant for using Dalkey Sound is the tidal currents that run strong through Dalkey Sound and the key to using it is to catch a fair tide, Neap rates attain 1.5 knots, Springs 2.5 knots as follows:

  • • The northwest going stream begins at Dover -0600, HW Dublin +0555

  • • The southwest going stream begins at Dover HW, HW Dublin -0030

Further offshore and in Muglins Sound the tides are as follows:

  • • The north going stream begins at Dover -0530, HW Dublin -0600

  • • The south going stream begins at Dover +0030, HW Dublin HW

A vessel of moderate speed is better off to avoid Dalkey Sound during an adverse tide. During these times the outer channel through Muglins Sound would be better or to pass further offshore.


The complete course is 0.83 miles from the waypoint 'North Approach to Dalkey Sound' to 'South Approach to Dalkey Sound' tending in a south south easterly direction (reciprocal north north westerly).

North Approach to Dalkey Sound, 53° 16.820' N, 006° 5.760' W
This is located 200 metres northwestward of Maiden Rock.

       Next waypoint: 0.44 miles, course 155.14°T (reciprocal 335.14°T)

Middle of Dalkey Sound, 53° 16.420' N, 006° 5.450' W
This waypoint is off Dalkey Island's northwestern point, to the mainland side of a centre channel path.

       Next waypoint: 0.39 miles, course 162.08°T (reciprocal 342.08°T)

South Approach to Dalkey Sound, 53° 16.050' N, 006° 5.250' W
This ¼ southwestward of the Martello Tower on Dalkey Island.


The below-listed waypoints will set up a passage through the sound and provide some guidance. The vast majority of the passage is made utilising eye-ball navigation.

Vessels passing between Dalkey and the mainland should prefer the mainland side keeping about 100 metres off the shoreline. The shore of the mainland is steep-to and all dangers are off the Dalkey Island side. A reef that extends to the northward of the island group has straggling outliers on both sides of it. Favouring the mainland’s steep-to shoreline side of the sound avoids all issues of the dangers.

Sorrento Point and Dalkey Sound seen from the distant south
Image: Michael Harpur

Southern Approach Vessels approaching from the south will find Killiney Bay to be composed of a shingle beach that is foul along the shoreline. It is best to keep half a mile off where there will be in excess of 10 metres of water. The Frazer Bank resides to the south east of Dalkey Island. With the least depth of 5.3 metres, it presents little issue for a leisure craft.

Yacht entering the south end of Dalkey Sound
Image: Michael Harpur

The single issue with Dalkey Sound are the tides that run strong here. The tides wrap around the Killiney Bay and may be felt abeam on approach or exit south of Sorrento Point. Look out for overfalls caused by the reconnection of tide runs that wrap around the island in this location also. Other than that enjoy the ride.

Northbound yacht passing through Dalkey Sound
Image: regienbb via CC BY 2.0

Align a central path of approach and keep well off the island as Dalkey’s southwest corner is foul. From beneath the islands southern gun battery, a reef extends 50 metres along the island’s western shoreline to about halfway along the coastline to the area of the Martello Tower.

Small boat passing Maiden Rock and out the north end of Dalkey Sound
Image: Michael Harpur

There is a drying rock scarcely awash close to the south of the landing steps near the ruin of the old church. To the north of the steps, another reef with 0.6 metres over it runs out 70 metres from the shore.

Dalkey Island and Dalkey as seen from the north
Image: regienbb via CC BY 2.0

Northern Approach Vessels approaching from the north should identify the rocks extending six hundred metres from the northwest ridge of the Island. The leading rock is Maiden Rock, or Carraig Rock, that stands 11 metres high and is always visible.

Southbound yachts passing Maiden Rock
Image: CC0

After this, there are several rocks such as Clare Rock and Lamb Island that are all parts of a large ridge extending north-westward from Dalkey Island of which some are only visible at low tide.
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.

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