The Mander[1] is one of the longest and largest rivers in Westeros. The Mander and its tributaries (including the Blueburn and the Cockleswhent) extend across much of the Reach, helping make it the most fertile part of the continent. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.