Like Avalon, the Cliffs of Dooneen are not found in a specific place, but in the mists of myth and nostalgia.

Blear version

I have travelled afar from my own native home
Away over the mountains, across the white foam
But give me a home where the grass grows so green
By the old mossy slopes on the Cliffs of Dooneen

How nice tis to walk on a fine summer’s day
And to view the Skereens* that will never decay
Where the sea grass (1) and sea weed and old carraigeen
Grow rich on the rocks by the Cliffs of Dooneen

The sandhills of Beale (2) are lovely and grand
And the old castle’s ruins (3) look out towards the strand
The rabbits in plenty today can be seen
Making holes for their homes by the Cliffs of Dooneen

My footsteps retreat to the boathouse of old
And the dance at the clash where love stories are told
Today you can see each lad and colleen
Walking round by the shore near the Cliffs of Dooneen

Farewell to Dooneen farewell for a while
And to all the nice neighbours I left on that isle
May my soul never rest till I lay on the green
On the old mossy slopes by the Cliffs of Dooneen

NOTES
1) these sea floor plants often grow in large "meadows" that resemble grazing. There are various types of red algae found along the coasts of Ireland - Great Britain: the alga dulse (Palmaria palmata) and the irish moss (Chondrus crispus also called Carragheen) which, when spread out and dried in the sun, turns to white in a characteristic "blonde" color!
* I still don't know the meaning of the word the Skereens (any algae?)
2) Corcas and Sandhills at Beal Point
3) in Beal you can still see the ruins of Beal Castle; it is interesting to read in the brief description of the ruins to mention the presence of numerous rabbit holes.

See for reference locations https://breenjohnny.wixsite.com/beal
My analysis in Terre Celtiche Blog
https://terreceltiche.altervista.org/cliff-dooneen-or-avalon/