Question: How far away is the mountain that is highest among Mourne Mountains from the Irish Sea?

Context articles: Mourne Mountains
Slieve Bearnagh
Newcastle, County Down
Annalong
Tollymore Forest Park
Ben Crom
Slieve Donard
Atticall
Slieve Binnian
Shimna River

The Mourne Mountains ( ; Irish: "na Beanna Boirche" ), also called the Mournes or Mountains of Mourne, are a granite mountain range in County Down in the south-east of Northern Ireland.
 It includes the highest mountains in Northern Ireland and the province of Ulster.
 The highest of these is Slieve Donard at 850 m .
 The Mournes is an Area of Outstanding Natural Beauty and has been proposed as the first national park in Northern Ireland.
 The area is partly owned by the National Trust and sees a large number of visitors every year.
 The name "Mourne" (historically spelt "Morne") is derived from the name of a Gaelic clann or sept called the "Múghdhorna".
Slieve Bearnagh (from the Irish: "Sliabh Bearna" ) is a mountain in the Mourne Mountains, Northern Ireland.
 Its summit is crowned by a number of rocky tors.
 The Mourne Wall crosses the summit of Slieve Bearnagh east to west.
 Paths lead to the cols on either side of the mountain, namely "Pollaphuca" ("pool of the púca") to the west and "Hare's Gap" to the east.
 From the latter, one can also descend southwards to the head of the Ben Crom reservoir.
Newcastle is a small seaside resort in County Down, Northern Ireland, which had a population of 7,444 at the 2001 Census.
 It lies on the Irish Sea at the foot of Slieve Donard, one of the Mourne Mountains, and is known for its sandy beach and the Royal County Down Golf Club.
 The town lies within the  Newry, Mourne and Down District Council area.
Annalong (from Irish: "Áth na Long" , meaning "ford of the ships" ) is a seaside village in County Down, Northern Ireland at the foot of the Mourne Mountains.
 It is situated in the civil parish of Kilkeel and the historic barony of Mourne.
 It had a population of 1,778 people at the 2001 Census and lies within the Newry and Mourne District Council area.
 The village was once engaged in exporting dressed granite and is now a fishing and holiday resort.
 Annalong Primary School is in the village and Annalong Community Development Association was established in 1994.
Tollymore Forest Park was the first state forest park in Northern Ireland, established on 2 June 1955.
 It is located at Bryansford, near the town of Newcastle in the Mourne and Slieve Croob Area of Outstanding Natural Beauty.
 It covers an area of 630 ha at the foot of the Mourne Mountains and has views of the surrounding mountains and the sea at nearby Newcastle.
 The Shimna River flows through the park where it is crossed by 16 bridges, the earliest dating to 1726.
 The river is a spawning ground for salmon and trout and is an Area of Special Scientific Interest due to its geology, flora and fauna.
Ben Crom (from Irish: "Binn Chrom" , meaning "curved/stooped peak" ) is a 526 m mountain in the Mourne Mountains in County Down, Northern Ireland.
 It is situated beside Ben Crom Reservoir, which is upstream from Silent Valley Reservoir.
 The mountain is composed of granite.
 An exposed area on the south west of the mountain shows where the Eocene aplitic granite meets the laccolith top of the older Mesozoic granite ring dike.
 The summit of the mountain features granite crags which are crossed by basic and feldspar porphyry dikes.
 The mountain is used for sheep grazing and hill walking.
Slieve Donard ( ; from Irish: "Sliabh Dónairt" , meaning "Dónairt's mountain" ) is an 850 m mountain in County Down, Northern Ireland.
 Part of the Mourne Mountains, it is the highest peak in Northern Ireland and in the wider province of Ulster.
 It is also the 19th highest peak on the island of Ireland.
 Slieve Donard sits near the town of Newcastle on the eastern coast of County Down, only 2 miles (3 km) from the Irish Sea.
Attical or Atticall (from Irish: "Áit Tí Chathail" , meaning "place of Cathal's house" ) is a small village and townland (of 396 acres) in the Mourne Mountains of County Down, Northern Ireland.
 It is situated in the civil parish of Kilkeel and the historic barony of Mourne.
 In the 2001 Census it had a population of 153 people.
 It lies within the Newry and Mourne District Council area.
Slieve Binnian (from Irish: "Sliabh Binneáin" , meaning "mountain of the little peak" ) is one of the Mourne Mountains in County Down, Northern Ireland, 9km north of Kilkeel.
 It is the third highest mountain in Northern Ireland at 747 m .
 The summit is broad and flat with rocky tors at the north and south ends, with the "Back Castles", impressive towers of granite, in between.
 To the south-west is Wee Binnian (from Irish: "Broinn Bhinneáin" , meaning "breast of Binneán" ) (460m).
 It lies to the east of the Silent Valley Reservoir and the west of the Annalong Valley.
 The Mourne Wall also crosses over Slieve Binnian.
The Shimna River (Irish: "Simhné" , meaning river of bulrushes) is a river in County Down, Northern Ireland.
 It rises on the slopes of Ott Mountain, in the Mourne Mountains, and enters the Irish Sea at Newcastle, on Dundrum Bay.
 It is acidic and nutrient-poor, as a result of which its most common flora are mosses and liverworts, including the rare Portuguese feather-moss and Holt's mouse-tail moss.
 Its principal fish are salmon and sea trout, and it is managed by the Shimna Angling Club.
 The river is an Area of Special Scientific Interest (ASSI).