Gregory’s Sound

The dive

Gregory's Sound — Sunda Ghríora — is the three-kilometre stretch of water separating Inis Meáin from Inis Mór, named after a hermit who lived on Inis Meáin. It is a tidal channel with a north-east/south-west stream running through it, and it is capable of confused seas in the wrong weather, so it is dived on the operator's judgement of the day rather than on a fixed plan. Dive Aran, the dive centre at Lower Kilronan on Inis Mór, lists it as one of its regular boat sites: about ten minutes from the pier in front of the centre, rated for beginners, with a maximum depth of 18 metres.

That combination — short crossing, shallow limestone ground, sheltered by two islands — is what makes it the sound's usable dive rather than a channel to be crossed. The Aran seabed here is the same fissured limestone that forms the islands above water, worked over by kelp, and the records from this pin are dominated by one animal: grey seal, logged more often at this position than everything else combined. Common dolphin and harbour porpoise are recorded in the sound too, and basking shark, which Dive Aran says is often spotted around the islands in spring and early autumn.

The rest of the dive is standard Aran cold-water life at close range: cuckoo, ballan and goldsinny wrasse, lesser-spotted dogfish, lobster, edible and spider crab, spotted ray, tompot blenny, and on the rock the sponges, hydroids, sea urchins and nudibranchs that make an Atlantic limestone wall worth a torch. Water runs from about 10 °C in spring to 18 °C in late summer and Dive Aran works in 7 mm wetsuits year-round rather than drysuits; visibility across their sites ranges from five metres to over twenty.

Gregory's Sound is one of sixteen named sites Dive Aran runs from Kilronan, and it is at the shallow, gentle end of that list — the Wormhole, the Tower and the Puffing Holes are the harder dives. Nothing is published about the site beyond the operator's own listing, so what follows is a beginner-grade boat dive in a tidal channel, not a documented topographic feature.

• Grey seals, the single most-recorded animal at this position
• Fissured Aran limestone under kelp
• Ten minutes from the pier at Kilronan
• Shallow enough at 18 m for a long, relaxed dive
• Basking sharks possible in spring and early autumn

Conditions

A short crossing from Kilronan into a sheltered but tidal channel, shallow limestone and kelp under the boat. Dive Aran quotes water of roughly 10 °C in spring to 18 °C in late summer across its sites and visibility anywhere from five metres to over twenty. Dive time on their trips is about 45 minutes.

On current: Gregory's Sound is a tidal channel: Afloat records a north-east/south-west tidal stream running through the three-kilometre gap between the islands, and notes it can throw up confused seas in certain weather. Dive Aran nonetheless rates the site as a beginner dive, which means they run it on the state of tide and weather that suits, not on demand. Assume the guide picks the window; do not plan this one independently without local tidal knowledge.

Best months: May, Jun, Jul, Aug, Sep

Dives & underwater footage