Fire crews battling a gorse blaze on Howth Head have contained the outbreak.
Firefighters have been using buggies from Howth golf club to transport equipment on the hill where the fire burned about 2km square at the top of the headland.
John Keogh, operations officer with Dublin Fire Brigade, said his teams were working to keep the blaze away from homes.
"It's arduous work here for firefighters moving up and down the hill," he said.
The fire broke out at about 3pm on Wednesday afternoon but it is not clear if it was started maliciously. Flames reportedly reached as high as 15 feet in some places with a thick plum of smoke from the headland visible across Dublin Bay.
Four fire engines with about 20 crew were on site for hours to prevent the blaze from moving toward homes.
A fire break was created at the top of Howth Head towards the back end of Howth golf course to contain the blaze with gorse, fern and grass beaten down and dampened near a pathway.
Mr Keogh said the fire could have been started youngsters messing around and a small fire getting out of control or by a discarded cigarette, a barbecue or a glass bottle lying under strong sun rays.
"We don't know what started it, it could be malicious or an accident," Mr Keogh said.
"Every summer we are up in Howth or the Dublin mountains dealing with something like this. Every three or four years we get a big fire because the grass and gorse has grown very tall and dry - it's just like kindling."