Passengers on a sea excursion off Achill Island in County Mayo were treated to a most unusual encounter. As their boat was returning from Achill Head, a sunfish, or Mola mola, surfaced near Keem Bay and approached the vessel.
The sighting was all the more spectacular because the sunfish is considered the world’s heaviest bony fish. Some individuals can grow to around 3.2 metres in length and weigh up to 2.3 tonnes. The sighting came just weeks after several appearances by a humpback whale in the same waters.
A sunfish spotted near Keem Bay
A rare encounter on an excursion around Achill Island
The sighting took place in early September during a trip organised by Achill Sea Safari. On the return journey from Achill Head, the crew spotted the fish at the surface near Keem Bay, one of the island’s best-known bays.
The Mola mola came close enough to the rigid inflatable boat for passengers to observe it. Footage of the encounter was subsequently shared by RTÉ on 7 September 2026.
Seeing a sunfish in Irish waters remains unusual, though not impossible. The species is found mainly in tropical and temperate waters, and can occasionally be seen from boats around Ireland, particularly during the summer months.
What is a sunfish?
The heaviest living bony fish
With its almost circular, laterally flattened body, small mouth and enormous dorsal and anal fins, the sunfish has a silhouette that is hard to mistake for any other marine animal. Its shape gives it the English name ocean sunfish, while its scientific name is Mola mola.
The largest specimens reach impressive dimensions. RTÉ notes that the species can grow to around 3.2 metres and weigh up to 2.3 tonnes. Despite its size, the sunfish is not a dangerous predator to humans.
It can be seen close to the surface, sometimes lying on its side. This striking behaviour has contributed to its name in several languages, and occasionally allows boaters to spot its large fin above the water.
Why are sunfish found in Ireland?
An occasional visitor to Irish waters
The appearance of a Mola mola off the Mayo coast does not mean the species has suddenly established itself in Ireland. Sunfish can be encountered in the North Atlantic and are occasionally reported in Irish waters during the most favourable months.
Atlantic currents and the biological richness of the waters west of Ireland support a particularly varied marine fauna. Depending on the season, and with a great deal of luck, sea excursions may offer sightings of dolphins, seals, basking sharks and different species of cetaceans.
An isolated sighting alone cannot, however, support any conclusion about a change in the species’ presence or about climate change. Above all, it is a rare encounter with an animal capable of travelling vast ocean distances.
A humpback whale had already caused a stir at Achill
Two remarkable sightings just weeks apart
The sunfish is not the only marine giant to have recently surprised visitors to Achill. In the preceding weeks, a humpback whale had been sighted several times in the island’s waters.
According to information reported by RTÉ, it was the first humpback whale sighting in Achill waters in 14 years. The sunfish was spotted around two weeks after that first encounter.
The succession of sightings is above all a striking reminder of the richness of Mayo’s Atlantic coast. The deep waters, islets, cliffs and bays around Achill create an environment where wildlife encounters remain, by their nature, unpredictable.
Keem Bay, a spectacular setting for this encounter
One of Achill Island’s iconic bays
The location of the sighting adds another dimension to the story. Keem Bay lies at the western end of Achill Island, between steep slopes that plunge towards the Atlantic. Its beach and turquoise waters have made it one of County Mayo’s most photographed landscapes.
The bay also has a history closely tied to the sea. Fishing, boat travel and marine wildlife watching are part of the identity of this part of the island.
Sea excursions around Achill offer a chance to get close to a coastline that is difficult to reach from land, made up of cliffs, caves, coves and Atlantic-exposed headlands. Wildlife encounters are of course never guaranteed: that is precisely what makes the appearance of a sunfish weighing several hundred kilos near the boat so memorable.
Watching marine wildlife at Achill without disturbing it
Encounters that must remain wild
Sunfish, dolphins, basking sharks or whales: the appeal of a sea excursion lies in the chance to observe animals in their natural environment. It also means keeping an appropriate distance, not attempting to touch or feed the animals, and allowing wildlife to decide whether to approach.
At Achill, Atlantic weather is also a decisive factor. Excursion routes may change depending on sea conditions and the weather on the day.
The passengers near Keem Bay in early September had no guarantee of encountering a Mola mola. They simply happened to come across, at just the right moment, one of the Atlantic’s strangest and most imposing fish.
