The Moonshae Isles were a group of islands that formed a roughly circular archipelago with the Sea of Moonshae in the center. They lay roughly 400 miles (640 kilometers) west of the region of Amn and to the southwest of the Sword Coast.[citation needed] Along the coasts, long flat beaches were found. Most lacked sand, and instead comprised pebbles and rocks. Tides were significant among the islands. At low tide, the beaches could be exposed as much as a quarter mile (400 meters) from the waterline. At high tide, the water line could rise up to 10 feet (3 meters). During storms, the beaches were battered by waves. The coastlines of the islands were dotted with bays and coves, where ships could find a safe harbor from the harsh northern seas.[10] The remaining coastlines were jagged rocks. Tall cliffs of granite towered over the water, some up to 500 feet (150 meters) in height. These cliffs were worn smooth from exposure to the wind, and in the winter were covered with sheer ice.[10] Further inland, stagnant saltwater marshes were usually found. These gray and desolate marches lacked trees and an odor of sulfur hung constantly in the air. Traveling in these marshes was hazardous, with about 10% of the terrain being quicksand.[10] Some of the fens and swamps in the Moonshaes rivaled those found in the jungles of Chult. These putrid and decaying swamps were filled with stagnant water. The Fens of the Fallon, on the island of Gwynneth, was likely the most dangerous area in all the Moonshaes.[11] Freshwater streams were common on the islands. Most were shallow, reaching a maximum depth of 3 feet (91 centimeters). Most streams were not safe for boats because of rapids. The islands were home to a handful of rivers, which were deeper and calmer, and safe for boats. Ferries and bridges allowed for safe crossing.[11] Much of the Moonshaes terrain was moorland. This rolling grassland was dotted with lakes, ponds, and swamps, but most of it was well-drained and dry. The terrain was safe and pleasant and was used as pasture for cattle and sheep.[10] Mountains and highlands made up another sizable portion of the Moonshaes terrain. These rugged and twisted mountains were jagged and cracked from centuries of erosion. The steep mountains reached 8,000 feet (2,400 meters) in height. From autumn to early spring, heavy snow covered the highlands, only melting away completely by summer.[12]