It is roughly 7 kilometres (5 mi) south of Dublin city centre and is situated on and around the hill of the same name.

As one travels south from the city centre, Mount Merrion is the first neighbourhood of any significant elevation above sea level.

It is a landscape known to every visitor to Ireland who has stood on deck as the Holyhead mail steamer passes the Kish lightship.

Around the wood some 1.2 km² (300 acres) of the richest grazing land in County Dublin slope gently to the high stone wall which surrounds the demesne.

To the north, the long low line of the Mourne Mountains, 100 kilometres (60 mi) and more away, are clearly visible when recent rains have left the washed air clear, while the islands of Lambay and Ireland's Eye give an added beauty to the sea-scape which lies beyond the wind-blown causeway which leads on and up to the rhododendron covered slopes above the ancient castle of Howth.

A double avenue of beech trees shades the roadway which runs, straight as a rule, for a full quarter of a mile to the entrance gates on the Stillorgan Road.

This roadway, whose immaculate pebbled surface was raked daily, had a broad border of century-old shaven turf, the pride of the Scottish gardener; so tended, brushed and rolled was it in those days that the most careless visitor would have hesitated to sully the velvety perfection of the surface with a profane foot.

Yet the gardener, his voice, with its rich Highland brogue quivering with fury at the bare recollection, would tell how a distinguished citizen of Dublin, having ridden to pay his respects to his lordship, had, on departing, cantered gaily down the sacred border, divots flying from his horse's heels; so that the whole length was scarred and pitted with hoofmarks, as though the plague had passed over it, and it was only after months of patient labour that the unbroken serenity of the surface was restored.

Merrion features on the 1598 map, "A Modern Depiction of Ireland, One of the British Isles" (by Abraham Ortelius as "Mergon").

Mount Merrion was occupied for a time by the Fitzwilliam agent Barbara Verschoyle and her husband, then Lord Herbert of Lea, and later by Sir Neville Wilkinson, from 1903 to 1914.

Crowds also gather in Deerpark to look out at the annual Skyfest fireworks display around St. Patrick's Weekend which is sometimes held in Dublin city centre.

It can also be a good vantage point for observing the Northern Lights, also known as the Aurora Borealis when they are visible in the Dublin area.

Maps such as John Roque's (1760) and Barker's Estate Maps (1762) show much of what is now Deerpark as a formal walled garden and many of the prominent avenues and boundaries of the nearby Mount Merrion House lands form the basis of the present local road network.

[citation needed] A local school, Scoil San Treasa, plays both Gaelic football and hurling.