Mount Leinster is the highest mountain in both Counties of Carlow and Wexford, courtesy of the county border which runs through the summit. It is also the fifth highest mountain in the province of Leinster at 796 metres (2,611 ft). It is to be found in the Blackstairs Mountains that run roughly North/South between the counties.
The mountains are composed of granite, locally known as Blackstairs Granite, which in turn forms part of the larger Leinster Granite massif. Extending from the Carlow-Wexford area northeast to Dublin Bay, the Leinster Granite is the largest body of granite in Ireland and Britain. It was emplaced, into the Lower Palaeozoic rocks towards the end of the Caledonian mountain building period, during early Devonian times (around 400 million years ago). The intrusion of the granite cooked and metamorphosed the surrounding native rock as it was emplaced, turning these mudstones into such stuff as micaceous phyllites and schists! (These are the shiny, slightly metallic looking rocks that can be found along side the granite on the mountain).
The mountain is quite recognisable from a distance as a large distinctive (some say obtrusive) transmitter sits on the summit. This transmitter is owned and operated by 2RN (RTE Networks) and at 796m above sea level it is the highest transmission site in Ireland. It was one of the original five main Telefís Éireann transmitters, opening on the 12 June 1963 with a 625-line service on Channel F. VHF FM radio transmission was added in 1966, with UHF television starting in 1996. The original mast was replaced in 2010 with a taller one of 130 m in preparation for digital terrestrial transmission.
Looking East
The route to the top is straight forward and is along the obvious paved road. The gate is seldom open so walking is the preferred means of locomotion. For the more adventurous and physically fit amongst us, taking the bike is also an option – but note this is not for the faint hearted, either going up or coming down!
As far as I can work out (and I am open to correction on this), the summit of Mt Leinster is the highest point in Ireland that it is possible to drive up to in an ordinary car. This depends of course on the gate being open, but it seldom is.
Other points of interest include The Nine Stones which are very near the parking co-ords.
In September 1983 a Cesena aircraft flying from Birmingham to Kilkenny crashed into the summit of the mountain, all four occupants were lost.
You might also see some hand gliders nearby riding the updrafts, apparently this is one of the best sites in Europe for this particular pursuit.
The cache is a small wrapped tupperware box placed about 30 m from the trig point. The sky view is excellent so the co-ords should be pretty exact. The weather can be pleasant at the parking spot but the summit can be windy and cold, be prepared.