Dalkey Island lies off the east coast of Ireland on the southern point of the entrance to Dublin Bay and about two and a half miles southeast of Dún Laoghaire Harbour. The anchorage is in Dalkey Sound off the northwest corner of the uninhabited and interesting Dalkey Island.

Although providing good protection from westerly and easterly conditions. However, having moderately reliable holding this can only be classed as an exposed anchorage owing to the sound’s strong currents and funnelling winds. It is best avoided in any brisk conditions from the northwest through northeast, or southwest through southeast, particularly so in wind-over-tide conditions that make it particularly uncomfortable. Daylight approaches are straightforward as the sound’s fairway is deep and clear following an approach off the mainland’s steep-to shoreline.

Because of the strong tides and funnelling winds it is not a place to leave a boat unattended for any period. If landing a shore party to visit the island it would be prudent to leave a competent crew member on board.

Keyfacts for Dalkey Island

Position and approaches

Haven position

53° 16.349' N, 006° 5.239' W

In the anchorage area, eastward of the white painted well.

What are the initial fixes?

The following waypoints will set up a final approach:

(i) Dalkey Sound north approach initial fix

53° 16.750' N, 006° 5.730' W

This waypoint is in the channel half a mile northwest of the anchorage.

(ii) Dalkey Sound south approach initial fix

53° 16.140' N, 006° 5.240' W

This waypoint is in the channel 400 metres south of anchorage.

What are the key points of the approach?

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What's the story here?

Dalkey Island is situated off the south point of the entrance to Dublin Bay about 500 metres east of the mainland’s easternmost Sorrento Point. It is an uninhabited 22 acre island that is 600 metres long northeast to southeast and rises to a 24 metres high summit where a Martello tower stands. Dalkey Sound lies between the island and the mainland. Having from 6.8 to 12.6 metres of water in the fairway, and a width of about 230 metres it provides a clear passage. The island anchorage is situated on the northeast side of the island within Dalkey Sound through which it is approached.




The traditional anchoring area lies in the Sound in about 4 - 5 metres to the north of the midpoint of the island abreast of a conspicuous white painted well on the island. The seabed is rocky with indifferent holding and this is a prime concern as the tides funnel through the Sound attaining speeds of up to 1.5 to 2.5 knots. Landing on the island is however greatly convienienced by the Dalkey Island Pier, also known as the Boat Harbour, located on the northwest coast of Dalkey Island close to that anchoring area.

How to get in?

Vessels approaching from the north and Dublin Bay will clearly see the 24 metres high Dalkey Island from across the bay. About 600 metres to the northeast of Dalkey Island there is a smaller 6 metres high rock islet called the Muglins. The Muglins is a different rock group that are not connected to Dalkey Island. A lighthouse on the 6 metres high Muglins, more aptly described as a distinctive beacon, makes it highly recognisable. It is a white conical tower with a red band standing 9 metres Fl 5s range of 11M. The anchorage is waiting Dalkey Sound and being approached through the sound is best described in the Dublin to Killiney Bay via Dalkey Sound .

The tides will be the primary concern as funneling through the Sound they attaining speeds of up to 1.5 to 2.5 knots. There are often overfalls caused by the reconnection of tide runs that wrap around the island just off Sorrento Point.



Anchor in 4 to 5 metres to the north of the midpoint of the island abreast of the white-painted well. As already mentioned the seabed is rocky so it provides indifferent holding and to also shelves steeply, so that anchoring too far out places a vessel in deep water. On the other hand, anchoring in shallower waters, places the vessel uncomfortably close to the island.



Land at Dalkey Island Pier close to the anchorage on the northwest corner of the island. A yelllow steel pole has been provided as a navigation aid to show the seaward end of the slipway. The pier and steps will be seen inside of this leading up to the grassy bank behind the boat harbour. The pier's access channel is 3.5 metres wide and is about -2.5m below mean tide levels so it only partialy exposed on extreme low tides. It can be broadly taken that good depths are available for tenders most all of the time.



Haul the tender clear of tne pier as the currents run strong here, and the pier should be kept clear as it is regularly used by local pleasure craft from Coliemore.

Alternatively, there is a little cove just alongside the slipway and the beach, to the west of ruin of the little Church of St. Begnet. This landing point may be used for the top two-thirds of the tide.

Why visit here?

Dalkey Island derives its name from the Danes who had a fortress and trading post here in the 10th-century. The original name 'Deilginis' was the conjunction of the Irish words deilg, meaning thorn, and inis meaning island, creating a name that basically means 'thorny island' but one that was heard as 'dagger island' or 'cloak-pin island'. The Danes simply borrowed deilg into their dálker and translated the inis into the Old Norse 'øy' or 'ey', meaning 'island' transforming the name into the present Dalk – ey.




As its Viking name suggests the small island is steeped in history with evidence of inhabitation that goes back 6,000 years to the 4th millennium BC. Excavated artefacts that present evidence of the island’s Mesolithic, or Middle Stone Age, occupation are housed in the National Museum in Dublin. They include Mesolithic Bann flakes, Neolithic hollow scrapers and Bronze Age arrowheads. Settlers continued to use the site throughout the Iron Age as is demonstrated by the promontory fort located at the northern end of the island. Worn by time, the fort is just perceptible today in the form of a ditch, which will be readily identified by those who know what they are looking for.




The island’s Early Christian period is well witnessed by the remains of the 9th or 10th-century St. Begnet stone church. An older wooden church was probably here before the present stone building and the existing ruin has been modified throughout the ages. The doorway lintel is typical of the period prior to the 12th-century and the church’s bellcote, high on the gable, is most likely to have been a 15th-century addition. The church takes its name from the patron saint of Dalkey St Begnet. The stories associated with her was that she was a beautiful and desirable princess, but she refused her numerous suitors in favor of religious devotion. Thus she was a 'virgin, not a martyr' and she has been identified with Saint Bega or other virgin saints named as Begha or Becga in Irish calendars. St. Begnet’s feast day is November 12. A Holy Well, situated near the Martello tower, is also associated with her and it is said to provide a cure for rheumatism.




The church was most likely abandoned when the Vikings used the island as a base and coined its name. During this time the island would have been one of the busiest ports in Ireland. This base for sea-going traders continued into the early medieval period when the island was a hub for the importation of goods from western France and the Mediterranean. This became increasingly the case from the 14th through to the 16th-centuries when Coliemore Harbour, immediately opposite the island, became Dublin’s principal port. At this time the dangers of Dublin Bay's shifting sandbanks and swallow channels, not to mention the constantly silting Liffey, was making it difficult for the then increasingly larger ships to navigate. The nearest alternative where vessels could anchor off was in the relative shelter Dalkey Island and in the deep waters of Dalkey Sound.




During this entire period, it was considered a very safe and convenient harbour where the tides of the Sound proved to a relied conveyor belt to help ships slip their berths. Cargoes for the capital where transferred 'to and fro' by lighters to Coliemore. Some of the cargos were then stored temporally in the medieval castle in Dalkey, otherwise they were directly transported to the capital by a causeway across Dalkey Common. This would most likely have taken the path of the current Coliemore Road location.




It was not until the 17th century that the issue of accessing the port of Dublin were stating to be addressed. Captain Bligh, famously the commander during the 'Mutiny on the Bounty', completed the charting of Dublin Bay in 1803 which became the most accurate chart of the time that vastly aided to the safety of mariners. His recommendations for the raising of the already established South Wall of the Liffey, and the construction of a second wall on the north side of the channel, if not in the form that the North Bull Wall takes today, all but resolved all the remaining issues. The completion of these walls transformed the fortunes of Dublin's shipping trade making it easier and safer for ships to enter the port and providing deeper depths along its quays. But, this in turn, eliminated the need for ships to use Dalkey Sound and all its trade ceased. Nevertheless, as late as 1815, Dalkey was surveyed as a site for an asylum harbour for the bay, if loosing out to the creation of the entirely new artificial harbour of Dún Laoghaire. The present-day harbour structure at Coliemore Harbour was constructed in 1868.




The most visible aspects of the island’s legacy today however are its British Admiralty defensive structures that date back to the 19th-century. Centremost amongst this is the island’s dominating and exceptionally large Martello Tower that was built on the island’s summit in 1804. During this period the little church served as living quarters for the workmen and it was then that the fireplace on the east side was added.




The Dalkey Martello is one of three 'double towers' built in Dublin to take two 18 pounder cannons on a roof platform - they were soon upgraded to 24 pounders. The Dalkey Island Martello was, originally, a totally unique design, as it is the only Martello tower known anywhere in the world to have been built without a doorway. The doorways of Martello towers were considered their most vulnerable point and because ships could sail entirely around Dalkey Island, it was seen to be vulnerable to seaward bombardment and designed out. Instead, the tower was accessed via a ladder that was secured to the roof. A large hatch was inserted through the 'bombproof' granite roof to allow stores to be hauled up and then lowered into the tower. The present entrance was a later insertion that leads directly into the magazine.

The guns on the tower were intended to work in tandem with the gun battery set into the island’s southern granite cliffs. Constructed at the same time as the Martello it housed three 24 pounders and was expanded and altered over time. Both structures combined to command the approaches to Dublin Bay, Coliemore Harbour and the Dalkey Sound anchorage, they made Dalkey Island the most heavily armed position in the chain of coastal fortifications. These and seven other towers, dotted along Dublin’s coastline, provided the capital with an early warning and defence system against the threat of a Napoleonic invasion that never came in the end. Military personnel were removed from Dalkey Island in 1886, it was one of the last of the Dublin towers to be disarmed.

Today, the Martello tower remains in local authority ownership and is currently locked up with no public access. Sometimes the lock on the door is broken and the tower accessed. The abandoned tower looks very similar to how it must have appeared when first completed but the battery gradually fell into ruin.

The small island is uninhabited today but there is plenty of wildlife here. It is host to a herd of goats that were originally brought here in the early 19th century. The current ones, however, are replacements of the original goats that were removed. Plenty of rabbits also live on the island. Offshore a colony of seals, which has greatly expanded in recent years, live around the rocky shores of the island. More recently a pod of three bottlenose dolphins have begun frequenting the waters around Dalkey Island.

Dalkey Island may offer the coastal cruiser an exposed anchorage but it is a location where it is well worth getting the dingy out. The island provides a magnificent walk through a scarcely trampled piece of national history. The views out over Dublin Bay, Killiney Bay and the Wicklow Mountains from both the Martello Tower and the ruined forts are simply spectacular.

What facilities are available?

Apart from the slip there are no facilities on this uninhabited island.

Any security concerns?

Never an issue known to have occurred at Dalkey Island.

With thanks to:

Charlie Kavanagh, ISA/RYA Yachtmaster Instructor/Examiner.