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Square Rock 12-22 mts
Ireland · reef · intermediate
12–22 mintermediateAOWboat entry
Square Rock 12-22 mts
Squared-off rock forming gullies and swim-throughs at 12 to 22 m in the channel between Inishtooskert and Illaunimmil; the only published description is one sentence long.
Max depth12–22 m
Required levelintermediate
Entry typeboat
Visibility20 m
The dive
Square Rock is a named dive in the Magharee Islands off Castlegregory, Co. Kerry, and it is worth being straight about how little is written on it. The entire published description is a single sentence from Waterworld Dive Centre, the only operator working these islands: the site takes its name from the shape of the rocks, which form gullies, and it offers swim-throughs and gullies. The depth range of 12 to 22 m comes from the same list and is baked into the name. Nobody else describes it, there is no trip report, and there are no photographs attached to any source we could find.
Waterworld files Square Rock under Illaunimmil Island, with The Inlet and The Necklace. The pin, which comes from the coordinates the centre itself submitted, sits about 400 m west of Illaunimmil and about 420 m south of Inishtooskert, in the channel between the two, so on the operator's own grouping the rock is on the Illaunimmil side of that channel. The neighbouring pins in the same catalogue are the four Inishtooskert dives, all within 600 m.
The ground around Illaunimmil was dived and described by BioMar in May 1996, which is the nearest thing to a real account of what is down there. The station south of the island, in the tide-swept channel between Illaunimmil and Illaunboe, found coarse sand over medium and large cobbles with kelp forest on the bigger boulders, Laminaria saccharina commonest and Laminaria hyperborea and Saccorhiza polyschides less so, over a patchy red-algal understorey. The station south-east of the island, at 20 m, found current-swept cobbles and pebbles with abundant foliose red algae, large clumps of the hydroid Sertularia argentea on the bigger cobbles, and brittlestars packed under the boulders. Both stations are within about 900 m of this pin, and both describe moving water.
NPWS designated the islands a Special Area of Conservation for reef: Carboniferous limestone, exposed on the western coasts and sheltered on the eastern, with moderately strong tidal streams between them, and reef built from boulder, cobble, pebble and sand over patches of solid bedrock, carrying kelp forest in the shallow sheltered parts. Occurrence records within 1.5 km of this pin list grey seal well ahead of anything else, then boring sponge and elephant hide sponge on the rock, spiny starfish, edible sea urchin, cotton spinner, lobster, edible crab, spiny spider crab and velvet swimming crab, pollack, ballan wrasse, goldsinny, rock cook, leopard-spotted goby and long-spined sea scorpion. Bottlenose dolphin, basking shark and ocean sunfish are all on record nearby.
- Squared blocks of rock forming gullies and swim-throughs, 12 to 22 m
- Sits in the tide-swept channel between Inishtooskert and Illaunimmil
- Kelp forest on the boulders in the shallows, Laminaria saccharina commonest, per the 1996 survey of the same channel
- Limestone reef inside the Magharee Islands SAC, designated for reef habitat
- Grey seal is the most-recorded animal around the pin, well ahead of anything else
Please note before you go
- Tide-swept channel between two islands: NPWS records moderately strong tidal streams there
- Swim-throughs and gullies, which become overhead ground in swell
- Depth of 22 m exceeds the 18 m limit Waterworld states for entry-level divers
- Cold water: 8 C early season, 17-18 C at the late-summer peak
- Boat access only, 10-15 minutes offshore, with no shore exit
Access & rules
Mandatory requirementsGetting there
Boat only, from Scraggane Pier at Fahamore north of Castlegregory, where Waterworld Dive Centre is based at Harbour House (V92 XFN7). Two boats go out daily and the centre puts its sites 10-15 minutes from the pier. Note the pin's position: the operator groups Square Rock with the Illaunimmil Island dives, while the coordinates it submitted put it roughly 400 m west of Illaunimmil in the channel toward Inishtooskert, so treat the pin as approximate to a few hundred metres.
Operator
Access to the site runs through a local operator.
Season
The months given are the warmest water, which is the only seasonal figure any source publishes for these islands: 8 C at the start of the season, 17-18 C in July, August and September, quoted identically by the operator and the Castlegregory community site. Neither gives an opening or closing date, and on exposed Atlantic reef the day-to-day limit is swell rather than temperature.
Conditions
Visibility20 m
Currentmoderate
Surgenot sourced
WaterSalt water
Depth range12–22 m
Environmentreef
Coralnot sourced
Crowdsnot sourced
Limestone reef in the channel between two exposed Atlantic islands: boulder and cobble over bedrock, kelp in the shallows, tide running through. Waterworld publishes about 20 m visibility on an average day, 40 m on the best and about 7 m on the worst, as a figure for its sites in general rather than this one. Water temperature runs 8 C early in the season to 17-18 C in July, August and September. Which side of the island group is diveable on any given day is decided by wind and swell.
On current: No source gives a current figure for Square Rock itself, but everything around it points the same way. NPWS records moderately strong tidal streams running between the Magharee Islands; the BioMar station south of Illaunimmil is described as a tide-swept channel, and the station south-east of the island at 20 m as current-swept cobbles and pebbles with clumps of Sertularia argentea, a hydroid the same survey treats as a marker of moving water. This pin sits in the channel between Inishtooskert and Illaunimmil rather than on the sheltered flank of either. Plan for current and take the operator's timing.
Best months: Jun, Jul, Aug, Sep
Questions & answers
How deep is Square Rock?
12 to 22 m, according to the dive centre that named it, with the range written into the site name. The 22 m bottom is below the roughly 18 m limit Waterworld quotes for entry-level divers, so it is normally an Advanced Open Water dive. No source gives a profile or a maximum beyond that range.
What is the dive at Square Rock actually like?
The honest answer is that almost nothing is published. The operator's entire description is one sentence: the site is named for the shape of the rocks, which form gullies, and it has swim-throughs and gullies. There is no trip report, no second account and no photography attached to any source, so expect the boat briefing to be your description.
Where exactly is Square Rock?
In the Magharee Islands off the Maharees peninsula north of Castlegregory, Co. Kerry. Waterworld groups it with its Illaunimmil Island dives, while the coordinates the centre submitted put it about 400 m west of Illaunimmil, in the channel toward Inishtooskert. Treat the pin as accurate to a few hundred metres rather than to the rock.
How do you get to Square Rock?
By boat only, from Scraggane Pier at Fahamore, where Waterworld Dive Centre operates from Harbour House. The centre runs two boats a day and says its dive sites are 10 to 15 minutes from the pier. It is the only operator publishing this site list, so access in practice means booking with them.
Is there current at Square Rock?
Assume yes. No source gives a figure for the site itself, but NPWS records moderately strong tidal streams between the Magharee Islands, and the two 1996 survey stations nearest this pin are both described as tide-swept or current-swept, one of them at 20 m. The pin sits in the channel between Inishtooskert and Illaunimmil rather than on a sheltered flank, so dive it on the operator's timing.
What will I see at Square Rock?
Nothing is named in the operator's one-sentence description. The 1996 survey stations either side of it found kelp forest on the boulders in the shallows and foliose red algae with hydroids and brittlestars on current-swept cobble at 20 m. Occurrence records within 1.5 km are led by grey seal, then boring and elephant hide sponge, spiny starfish, edible sea urchin, cotton spinner, lobster, edible crab, spiny spider crab, pollack, ballan wrasse, goldsinny, rock cook and leopard-spotted goby, with bottlenose dolphin, basking shark and ocean sunfish also on record.
Can you snorkel Square Rock?
No. The described dive begins at 12 m, the site is reached only by boat from a pier 10 to 15 minutes away, and it lies in a tidal channel between two offshore islands. Scraggane Bay at the pier, roughly 7 m over sand and sheltered behind the islands, is the snorkelling option in this area.
When is the best time to dive Square Rock?
June to September on water temperature, which the operator and the Castlegregory community site both put at 8 C early in the season and 17-18 C in July, August and September. It is drysuit or heavy semi-dry diving throughout. Neither source publishes a season, and on exposed Atlantic reef swell decides the day more than the month does.
Life recorded at Square Rock 12-22 mts
60 species within 1.5 km · OBISTursiops truncatusoccasional · 6 recordsMola molarare · 2 records
Halichoerus grypusoccasional · 17 records
Cliona celataoccasional · 9 records
Marthasterias glacialisoccasional · 8 records
Calliostoma zizyphinumoccasional · 8 records
All 60 species recorded in this area
| Species | How often | Records |
|---|---|---|
| Halichoerus grypus | occasional | 17 |
| Cliona celata | occasional | 9 |
| Marthasterias glacialis | occasional | 8 |
| Calliostoma zizyphinum | occasional | 8 |
| Echinus esculentus | occasional | 6 |
| Pachymatisma johnstonia | occasional | 6 |
| Tursiops truncatus | occasional | 6 |
| Homarus gammarus | occasional | 5 |
| Ophiactis balli | occasional | 5 |
| Thymosia guernei | occasional | 5 |
| Cancer pagurus | rare | 4 |
| Maja squinado | rare | 4 |
| Sertularia argentea | rare | 4 |
| Asterias rubens | rare | 4 |
| Aslia lefevrei | rare | 4 |
| Steromphala cineraria | rare | 4 |
| Holothuria forskali | rare | 4 |
| Clavelina lepadiformis | rare | 3 |
| Polyclinum aurantium | rare | 3 |
| Scyliorhinus canicula | rare | 3 |
| Necora puber | rare | 3 |
| Pollachius pollachius | rare | 3 |
| Taurulus bubalis | rare | 3 |
| Dysidea fragilis | rare | 3 |
| Raspailia (Raspailia) ramosa | rare | 3 |
| Aplidium nordmanni | rare | 2 |
| Aplidium punctum | rare | 2 |
| Ascidiella aspersa | rare | 2 |
| Botryllus schlosseri | rare | 2 |
| Dendrodoa grossularia | rare | 2 |
| Polycarpa scuba | rare | 2 |
| Cetorhinus maximus | rare | 2 |
| Obelia geniculata | rare | 2 |
| Luidia ciliaris | rare | 2 |
| Henricia oculata | rare | 2 |
| Ophiothrix fragilis | rare | 2 |
| Thorogobius ephippiatus | rare | 2 |
| Centrolabrus exoletus | rare | 2 |
| Ctenolabrus rupestris | rare | 2 |
| Labrus bergylta | rare | 2 |
| Mola mola | rare | 2 |
| Haliclona (Haliclona) simulans | rare | 2 |
| Hemimycale columella | rare | 2 |
| Tethya citrina | rare | 2 |
| Aplysia punctata | rare | 2 |
| Jorunna tomentosa | rare | 2 |
| Patella pellucida | rare | 2 |
| Amphilectus fucorum | rare | 2 |
| Haliclona (Haliclona) urceolus | rare | 2 |
| Antiopella cristata | rare | 2 |
| Halecium halecinum | rare | 2 |
| Botrylloides leachii | rare | 2 |
| Spongosorites calcicola | rare | 2 |
| Dercitus (Dercitus) bucklandi | rare | 2 |
| Polycera kernowensis | rare | 2 |
| Diplosoma listerianum | rare | 1 |
| Diplosoma spongiforme | rare | 1 |
| Aplidium turbinatum | rare | 1 |
| Diazona violacea | rare | 1 |
| Munida rugosa | rare | 1 |
Nearby sites in Magharee Islands, Castlegregory
Explore all sitesTHE POINT: 18-22mts.0.4 km
Magharee Islands, CastlegregoryBoulders, overhangs and anemone-covered canyon walls at 18 to 22 m, in the middle of the Magharee Islands where the dive centre's named sites cluster.
POLLACK ALLEY: 12-16mts0.4 km
Magharee Islands, CastlegregoryA 300-metre kelp wall dropping to sand at Inishtooskert, where big pollack hang over the sprat runs.
THE RIDGE HOLES: 10-22mts.0.5 km
Magharee Islands, CastlegregoryA ridge crest pocked with very large round holes, often with crawfish or spiny spider crab sitting in them, worked between 10 and 22 m.
THE GULLY: 8-20mts0.6 km
Magharee Islands, CastlegregoryA gully swum between two cliff faces on Inishtooskert, 8 to 20 m, with cave mouths off it the operator tells you to leave alone because of the swell.
The Necklace 8-16 mts0.6 km
Magharee Islands, CastlegregoryA kelp gully you work uphill to 5 m before dropping into a rock bowl at 12 m, at the sheltered eastern end of the Magharee Islands.
THE INNER REEF: 18-33mts0.9 km
Magharee Islands, CastlegregoryKelp on the top, then a clean rock wall running roughly half a mile down to sand at 33 m, on the landward side of Gurrig Island.
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