Very difficult to make out some of the lyrics, but maybe someone else can fill in the gaps.
The tune is traditional - I'm sure I've heard the late Michael O'Dhomhnaill [RIP] sing a song in Gaelic to the same melody, either with the "Bothy Band" or when he was in a duo with Kevin Burke. I'll try to track that down.
The Polydor record label credits words to "E,Furey, D.Arthur".

"Emigrant"

"When sweet [ days ? ] they do arise
And you hear that sounds of butterflies
Or the spirit of some [ crimson ?] rose
Or the echo of that [ sea sand shore ? ]
It is the hour I leave this place
Made fair by you and you alone
So here's Godspeed one last embrace
Way down below them stepping stones.

And in that stream long leaf flowers weep
Way down below that [ ??? ] strand
Like between a rainbow and the sun
My boat sets seaward from the land
And love may come and love may go
Just like that bird from tree to tree
But when she sleeps, her heart I know
Will wander with me on the sea"