Marine biologists believe three orca killer whales which have been in Cork Harbour since Sunday have come to teach their young how to navigate and find fish.
The whales, which range in size from a 30-foot male to a young 15-foot female, have been attracting hundreds of people to Cobh, Co Cork, since their arrival on Sunday. It is very unusual for orca whales to swim into confined waters.
The last time an orca was seen in Irish waters was in 1974 when a whale, nicknamed Dopey Dick, spent three days feeding in Lough Foyle.
Mr Eddie English, who runs the International Sailing Centre in Cobh, has been helping with efforts to return the creatures to the open sea.
He said the whales had a highly sophisticated sense of navigation and would know that they had travelled to confined waters.
"When they are fed they will go. There are several more pods of whales off Cork Harbour and these guys just seem to have taken an excursion. I have only seen an orca whale on the south coast of Ireland once before and that was 30 years ago. So this is very unusual."
Orcas are the largest members of the dolphin family and are very social creatures. The whales have 10 to 12 pairs of large teeth and can weigh up to 10.5 tonnes.
The familiar black-and-white coloration of the orca is actually a strategy of camouflage. From above, their dark back blends in with the darker water below them, while from below, their white bellies blend in with the sunlit water above.
The whales inhabit waters between the polar region and the equator, but they can adapt to almost any conditions and appear to be at home in both open sea and coastal waters.
Whale watchers say orcas do not deserve the name "killer whale". It is believed that mariners and whalers observed transient orcas eating other whales and named them whale-killers. Over time the name was reversed to killer whales. However, there are no confirmed records of orcas ever killing a person in the wild.
The orcas are expected to feed in Cork Harbour for another few days. It is thought that small boats in the area will disturb them, and as a result they will swim back out to sea.
Mr English says that people in Cobh hope the arrival of the orcas is a sign of good weather to come.
"We think that the arrival of the orcas is a sign of amazing weather and indicates that Cobh is going to be the busiest place in Ireland for the rest of the year," he said.