The Sound may be accessed through the People’s Park south of the Dalkey village. Pass through the village, veer past the Loreto Convent and about 200m after Colimore Harbour, up the hill there is a park on the left. Park on the road. Descent 60m towards the sea passing the statue of a goat, at the corner of the small field there is a small path through some bushes leading to the steps beside a large rock.
The bottom is at 10-12m on sand at the edge of the boulder shoreline. Visibility is usually 5-7m as the area is kept clear by strong currents. Keep close to the shore as the Sound can sweep a diver along at 4 knots. Access is easy at high tide but the steps dry out at 2 hours below low tide. A southeasterly swell can make landing difficult.
This is a good spot for a quick shire dive on a summer evening, the fish life rarely disappoints and lobster, crab and wrasse are common with dogfish and even squid appearing occasionally. This is also a favourite sea angling site so beware of lines tangled on the bottom. The park provides a suitable amusement area for any non diving companions.

Apart from the south eastern end of the island the diving is shallow, 8-10m, with rocks covered with thick kelp on a sandy bottom. This makes for interesting pottering about type diving, if you are into that sort of thing or an excellent place for a novice diver.
The south eastern end, under the old fort, starts in a similar manner but slopes away to 30m. The bottom consists of large boulders, rock ledges and patches of mud and sand. Below 20m it becomes very dark and a good torch is an absolute necessity. At 30m it is dark! The sea life is not as good here as on the Muglins but it may be dived in strong N/N/W winds and it is also suitable for the less experienced.
The strong currents of the area do not adversely affect diving provided on keeps away from Dalkey Sound where current speeds of up to 4 knots can occur at mid tide. The best dive plan is to submerge near, or to the east of the fort, swim out south-easterly underwater to your required depth and return on a reciprocal bearing to your starting point.
Do not continue into the current should you stumble across it. On ebb tides a strong rip current sweeps out of Dalkey Sound around the fort point. On the flood tide there is a strong to the East of the island.
Dalkey Island, which has a long history dating back to the Stone Age, gets its name from the Irish Delginis meaning Thorn Island. It was fortified by the Danes and later by the English and Napoleonic times. There is also a small medieval oratory. The island is unusual in having a herd of wild goats. A landing stage opposite Collimore Harbour facilitates exploration.

The island is oval shape and about 100m long and 17m at its widest, high at the northern end tapering off southwards. The rock is granite and has a cigar shaped, red and white navigation beacon on top. There is a small quay on the western side facing Dalkey Island.
The Muglins is populated by seagulls, shags, cormorants and other sea birds in the water. They are well used to human activity and the seals may even give your fins a playful nip.
The backbone of the island runs in a southwest direction, the flood tide sweeps out of Killiney Bay and around the Muglins to the northeast, on the ebb tide the current flows north to south resulting in slack areas around the rock no matter how strong the tide is flowing. On the flood tide the east and north sides are diveable and on the ebb tide the southwestern side is diveable.
There is a tidal rip visible at each end of the island, on the flood the south end and on the ebb the north end, which should be avoided.. It is inside these rip tides that diving is possible if you are unable to dive at slack water.
The best diving is on the eastern side, sea side, of the rock. The slope of the rock visible above the water continues underwater to about 30m. Tumbling down in a series of cliffs, ledges and boulders. The slope is steepest at the northern end but at the southern there is evidence of at least one wreck.
At depth it is possible to “see” where slack water ends and the current starts by observing the tumbling shells and weed a metre off while remaining in calm water. Do not enter the current unless it is part of your dive plan!
The western side of the island is shallower and less precipitous. If the tide is flowing it is only possible to dive between the landing stage and the southern point. The bottom slopes more gently out towards the sound in series of ledges, boulders and sand. Again beware of swimming out in the current, unless planned.
The nearest place where one can launch a boat is from the slip in Bulloch Harbour about 4km from the Muglins. Unfortunately this slip is tidal, and is only usable within 3 hours of high water. Dun Laoghaire Harbour, about 6km from the Muglins, has a public slip in the inner harbour but this too is tidal.
Boats may be hired in Bulloch Harbour. These boats are mostly used by fishermen and are wooden clinker built or fibreglass hulled with low powered engines.