Pollavurleen is hardly unique, but unique enough in Galway, and is in the modern Parish of Castlegar Galway.
What set it in the unique zone, is that waters from Lough Corrib, flow into Pollavurleen; disappearing into the ground - not in one location, but two.
This old place is connected by its mention in the events which are known as Lynch's Folly.
Pollavurleen, may have various spellings, and means Hole of the Sinking River. See http://places.galwaylibrary.ie/asp/fullresult.asp?id=20311
Primitive tests are said to include the tossing of Chaff into it, and attempting to locate it in various locations. Some will tell of its destination as Oranmore, while others will say Waithman's pier.
So, even the waters which drain from the contoured surrounding Castlegar and Glenanail Townlands, will presumably end up in Galway Bay without having to inconvenience the River Corrib, via the Sandy River.
See this place in a Dynamic map (new window).
Coordinates; 53.294517 , -9.023931
Hover your mouse over the image above, to see a newer image.
Old, Free maps, are available at http://www.galway.ie/en/Services/Library/1842OSMaps/
This area is also important in terms of Drainage Infrastructure - draining from the East as far as Kennys Garage on the Tuam Road (new network, circa 2007).
This may also be written as Poulavorline, and other variations.