The Three Sisters (Ireland) in the context of "River Nore"

Shown here are all the major rivers and tributaries of Ireland with their lengths (in kilometres and miles). Starting with the Northern Ireland rivers, and going in a clockwise direction, the rivers (and tributaries) are listed in regard to their entry into the different seas: the Irish Sea, the Celtic Sea and the Atlantic Ocean. Also shown are two tables. Table 1 shows the longest rivers in Ireland with their lengths (in kilometres and miles), the counties they flow through, and their catchment areas (in square kilometres). Table 2 shows the largest rivers in Ireland (by mean flow) in cubic metres per second.

The longest river in Ireland is the River Shannon, at 360.5 kilometres (224.0 mi). The river develops into three lakes along its course, Lough Allen, Lough Ree and Lough Derg. Of these, Lough Derg is the largest. The Shannon enters the Atlantic Ocean at the Shannon Estuary. Other major rivers include the River Liffey, River Lee, River Swilly, River Foyle, River Lagan, River Erne, River Blackwater, River Nore, River Suir, River Barrow (The Three Sisters), River Bann, River Slaney, River Boyne, River Moy and River Corrib.

The Barrow (Irish: An Bhearú) is a river in Ireland. It is one of The Three Sisters, the other two being the River Suir and the River Nore. The Barrow is the longest of the three rivers and, at 192 km (120 mi), the second-longest river in Ireland, behind the River Shannon. The catchment area of the River Barrow is 3,067 km before the River Nore joins it a little over 20 km before its mouth. The river's long term average flow rate, again before it is joined by River Nore, is 37.4 cubic metres per second. At the merger with the River Nore, its catchment area is ca. 5,500 km and its discharge over 80 m/s.

Waterford Harbour (Irish: Loch Dá Chaoch / Cuan Phort Láirge) is a natural harbour at the mouth of the Three Sisters; the River Nore, the River Suir and the River Barrow in Ireland. It is navigable for shipping to both Waterford and New Ross. The Port of Waterford is capable of accommodating vessels up to 32,000 tons dwt. It separates County Waterford from County Wexford on the eastern side of the estuary.

Dunmore East is a fishing village and popular holiday resort situated on the west side of the harbour and is generally considered to be the western limit. On the west side, there is also a headland called Creaden Head The eastern limit is Hook Head, marked by the Hook Lighthouse, on the Hook peninsula.