By boat from Rathlin or Ballycastle Harbour. From West Lighthouse, head east, hugging the coast for approx. 1km. From the entry point follow the contour east, staying close to the ridge which leads to a rocky slope. Turn north where the slope meets boulders and follow the steep rock round to the west, keeping the steep rock to your left. Find a series of small caves within the rocky wall and the Archway is found perpendicular to the cliff edge at around 28 metres.
Rathlin Harbour has pontoons for around 40 boats. Water and electricity are available on the pontoon but there is no reliable source of fuel. Public toilets are available in Church Bay between the harbour and the pub, near the playground.
Ballycastle Harbour has a gated slipway (open during office hours) and pontoon berthing. Free car parking is available above the harbour and marina. Free public toilets are available in the visitor information office above the harbour.
Berthing fees apply for both Rathlin and Ballycastle Harbour Office; for use of either, contact the Ballycastle Harbour Office: 02820768525 / 07803505984.
Nearest tank filling is Aquaholics in Ballycastle or Portstewart (ring ahead: 028 7083 2584)
- The north wall of Rathlin drops off to 200 metres where strong down currents are common.
- Strong tidal streams.
- Lobster pots and broken fishing lines are found on the site.
- Beware of swell from NW.
The upper shelf in this area is mainly at a depth of 23m. There is a second small shelf at approximately 33m from which the archway. The shelf itself is covered in small boulders. The top of the arch is at approximately 25m and the base at approximately 32m. The arch measures approximately 4m high and 8m wide. On the eastern side of the arch there is a small gully leading to a smaller second arch in 35m (2m high by 3m wide). The north side of this arch leads to a sheer cliff. On the shelf to the east of the large arch there are two caves and there is a further small cave immediately to its west side. On the east side of the arch there is a boulder slope, on the western side the shelf drops onto a sheer wall, part of the north wall.
The arch is densely encrusted with animal turf, including dead mans fingers Alcyonium digitatum, Devonshire cup corals Caryophyllia smithii, elephant’s hide sponge Pachymatisma johnstonia, the sandled anemone Actinothoe sphyrodeta and dense colonies of the sea squirts Dendrodoa grossularia and white Parazoanthus anguicomus, and yellow, Parazoanthus axinellae, cluster anemones. There is a large patch of the soft coral Alcyonium hibernicum on the underside of the arch towards its north (wall) edge.
View all species records from this siteA link to the dive site location on the NBN Atlas Northern Ireland website, showing all species records from within a 1km boundary of the site centroid. Any new species records from the site submitted to Seasearch, iRecord, CEDaR Online Recording or iNaturalist will appear here
Rathlin Dive Expedition 2019 Report
- In an emergency call 999 or 112 and ask for the coastguard.
- Follow VHF radio Channel 16 (156.8 MHz), the international distress frequency. Send a distress alert followed by ‘MAYDAY, MAYDAY, MAYDAY’ and ‘This is [boat name]’.
- Find nearest defibrillator (AED) here.
- Ballycastle/Rathlin Harbour Office No. 028 207 68525 Mobile Number 07803 505084
- When navigating within Ballycastle or Rathlin Harbour, use VHF Channel 80.
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