The Lake Isle of Innisfree does exist. It is a small island in the middle of
Lough Gill, a lake ("
Lough" = "
Loch") located in Co.
Sligo,
Ireland. Here is an excerpt from
William Butler Yeats' autobiography in which he explains the origins of this poem:
"(While in London,) I had various women friends on whom I would call towards five o'clock mainly to discuss my thoughts that I could not bring to a man without meeting some competing thought, but partly because their tea and toast saved my pennies for the bus ride home; but with women, apart from their intimate exchanges of thought, I was timid and abashed. I was sitting on a seat in front of the British Museum feeding pigeons when a couple of girls sat near and began enticing my pigeons away, laughing and whispering to one another, and I looked straight in front of me, very indignant, and presently went into the Museum without turning my head towards them. Since then I have often wondered if they were pretty or merely very young. Sometimes I told myself very adventurous love-stories with myself for hero, and at other times I planned out a life of lonely austerity, and at other times mixed the ideals and planned a life of lonely austerity mitigated by periodical lapses. I had still the ambition, formed in Sligo in my teens, of living in imitation of Thoreau1 on Innisfree, a little island in Lough Gill, and when walking through Fleet Street very homesick I heard a little tinkle of water and saw a fountain in a shop-window which balanced a little ball upon its jet, and began to remember lake water. From the sudden remembrance came my poem "Innisfree," my first lyric with anything in its rhythm of my own music. I had begun to loosen rhythm as an escape from rhetoric and from that emotion of the crowd that rhetoric brings, but I only understood vaguely and occasionally that I must for my special purpose use nothing but the common syntax. A couple of years later I could not have written that first line with its conventional archaism -- "Arise and go" -- nor the inversion of the last stanza."
1- Henry David Thoreau spent two years living as a hermit in the woods that circle Walden Pond, and describes this experience in an eponymous book.