The Killarney National Park Landscape

Hours, prices and access verified by the Killarney National Park Tours team — last checked August 13, 2026

Why the lakes sit where they do, why the north of the park is soft and the south is not, and what carved the Gap of Dunloe. Read in the order it happened, which is also the order you can see it.

Old Red Sandstone, laid down in the Devonian

The mountains here are built of Old Red Sandstone, a hard, acidic rock laid down under desert rivers long before anything walked on land. It resists weathering, it holds almost no lime, and it produces thin, sour soil. That single fact explains most of what grows in this park and most of what does not.

Every summit you can see from Ladies’ View is this rock. So is the ground under the oakwoods, which is why they are oakwoods and not something richer.

The limestone shelf, and why Lough Leane sits on it

North of the mountains the sandstone gives way to Carboniferous limestone, a softer rock that dissolves in rain. The boundary between the two runs roughly through the middle of the park, and the lakes have gathered along it.

Lough Leane, the largest of the three, lies almost entirely on limestone — which is why its shores are green and comparatively fertile while the mountain ground a few kilometres south is bare. Reenadinna yew wood grows on this limestone and could not grow on the sandstone.

That boundary splits the park in two, and almost every practical decision follows it. The northern, limestone half is lower, greener and carries the demesnes at Knockreer, Ross Island and Muckross, along with every easy waymarked trail. The southern, sandstone half is higher, wetter and carries the mountains and the strenuous routes.

What the ice did — corries, the Gap and the lake basins

Glaciers finished the job. They ground out the hollows the three lakes now fill, scoured the valley sides back to rock, and left the boulder-strewn ground you walk over on the higher trails.

The Gap of Dunloe is the clearest single piece of evidence: a deep, straight breach between the Purple Mountain group and the Reeks, cut by ice moving through a weakness in the rock. Standing in it, the scale of what moved through is obvious.

The Reeks on the skyline

The MacGillycuddy’s Reeks form the western horizon from almost everywhere in the park, and they hold Ireland’s highest ground. They are the same Old Red Sandstone, pushed up and then carved out, and they are what makes the view from Knockreer more than a view of a field.

They also make the weather. Wet Atlantic air hits them first and drops its rain on this valley, which is the next section.

Rain, and why everything is green

The Reeks wring the Atlantic out over Killarney. That reliable, heavy, year-round rainfall is why the oakwoods carry the depth of moss and fern they do, why the Killarney fern survived here, and why the whole place reads as green even in February.

It is also why every tour in this park runs in the rain. There would be no park worth visiting without it.

Reading the landscape from Ladies’ View

Stand at the viewpoint on the N71 and the whole story is in front of you. The Upper Lake in the hollow the ice cut, the sandstone ridges either side, the limestone country opening out toward Killarney in the distance, and the woods holding the lower slopes where the soil is deep enough.

It is nineteen kilometres from town and every Ring of Kerry coach stops there. If you only look at this park properly once, look from here.

The named landforms