The Irish Whale and Dolphin Group (IWDG) is investigating reports of up to 100 basking sharks spotted off Valentia island in Co Kerry. The species is the second largest fish in the world.
The fine weather has produced "a plethora" of sightings of whales, dolphins and sharks off the coast. According to the whale and dolphin group, more than eight basking sharks have also been confirmed off the Inishowen peninsula in Co Donegal.
While appearing to bask in the sun, the giant-mouthed sharks, which can weigh up to seven tonnes, are feeding on plankton.
Speaking on reports from Valentia of over 100 basking sharks in the area, Padraig Whooley, of the IWDG, said such a "huge aggregation" would be highly unusual although not unheard of in Irish waters. He stressed, however, that the Valentia sightings were unconfirmed.
Locals on Valentia yesterday reported seeing many porpoises and dolphins in recent weeks.
The whale and dolphin group website www.iwdg.ie is tracking the sightings.