The Rainbow Lake is the largest body of water in the Four Lands. It is located in the middle of Southland. It is widely used for fishing. Three Rivers flow into it: Silver, Rappahalladran, and Mermidon. Walker Boh and Hunter Predd flew on Obsidian over the lake on their way to the Hadeshorn.
"It was green and fresh, a mix of grasslands and forest, foothill and mountain. Water from the river and its dozens of tributaries fed the earth and kept it moist. Mist from the lake drifted north with each sunrise, dissipated, and settled into the land, giving life beyond the summer season" - The Wishsong of Shannara pg. 48