The legend of Fionn Mac Cumhaill and the Salmon of Knowledge is one of the most popular stories from Irish mythology.
It tells the tale of a young Fionn Mac Cumhaill, many years before he became the leader of the Fianna. It all began when he was taken on as an apprentice by a celebrated poet.
One day, the poet told Fionn the story of the Salmon of Knowledge, and that, if caught, it could make any man or woman the most intelligent person in Ireland.
The Salmon of Knowledge
Now, just to put it out there from the beginning – as is the case with many stories from Irish folklore, there are a number of different versions of the story of the Salmon of Knowledge.
The one that I’m about to tell you below was told to me as a child, over 25 years ago. God, 25 years… that’s a depressing thought!
The story all begins back when Fionn, who was still a child at the time, was sent to be an apprentice with a widely regarded poet, name Finnegas.
Hazel Trees and the Wisdom of the World
On one sunny Spring morning, Fionn and the old poet were sat down by the edge of the River Boyne. It was while they sat with their feet dangling over the water that Finnegas recounted the story of the Salmon of Knowledge to Fionn.
The story had been passed to Finnegas by an old druid (Celtic Priest). The druid had explained that there was a salmon that lived in the murky waters of the river.
Sounds pretty normal, right? Well, here’s where the plot thickens. The druid believed that the salmon, a magical Irish folklore creature, had devoured several nuts from a magical hazel tree that had grown near the river.
Once the nuts began to digest in the fishes belly, the wisdom of the world was given to it. Here’s the bit that sparked the interest of Fionn – Finnegas said that the druid believed that the person who ate the salmon would gain its knowledge.
Catching the Salmon of Knowledge
The elderly poet had spent many years gazing into the river in an attempt to spot and catch the Salmon of Knowledge.
Alas, he never came close. Then, one day while he and Fionn were sitting by the River Boyne, he saw the glint of an eye peering up from the water below.
Without hesitating, he dived into the water after the fish and managed to grab hold of it, much to both his and the young boy’s surprise.
All didn’t go to plan
Finnegas gave the fish to Fionn and asked him to cook it for him. The poet had waited years for this moment and he was worried that the young boy might betray him.
He told Fionn that under no circumstance could he eat even the tiniest sliver of the fish. Finnegas left as he needed to fetch something from his home.
Fionn did what he was asked and prepared the fish. After a couple of minutes, the salmon was baking away on top of a searing hot stone set above a small fire.
The Salmon had been cooking for a number of minutes when Fionn decided to turn it over to ensure that it was thoroughly cooked. As he did so, his left thumb glanced off of the meat.
Then came the knowledge of the world
It burned painfully and Fionn, without thinking, stuck his thumb into his mouth to ease the pain. He realised his mistake only when it was too late.
When Finegas returned, he knew that something was wrong. He asked Fionn what had happened and all was revealed. After taking a moment to mull the situation over, the poet told Fionn that he would have to eat the fish to see if he could gain its wisdom.
Fionn hurriedly devoured the fish but nothing happened. Clutching at straws, Fionn decided to stick his thumb in his mouth again, and that’s when it everything changed.
As soon as he put his thumb in his mouth he felt a surge of energy and knew that the wisdom given to the salmon by the magic hazel trees was now his.
The wisdom given to Fionn by the salmon made him the wisest man in Ireland. Fionn grew up to be the great ancient warrior that we know today.
Read more stories from the many adventures of Fionn Mac Cumhaill or check out our guide to five of the creepiest tales from Irish folklore.
Keith O’Hara has lived in Ireland for 35 years and has spent most of the last 10 creating what is now The Irish Road Trip guide. Over the years, the website has published thousands of meticulously researched Ireland travel guides, welcoming 30 million+ visitors along the way. In 2022, the Irish Road Trip team published the world’s largest collection of Irish Road Trip itineraries. Keith lives in Dublin with his dog Toby and finds writing in the 3rd person minus craic altogether.