Upper Underdark

The topmost level of the Underdark proper, the Upper Underdark is by far the most well explored by the dwellers from the surface world and it is regarded as being the most densely populated by creatures native to the Underdark. Some of the Underdark’s sapient species, such as Drow prefer to reside in the Upper Underdark, as it gives them more ready access to the surface to which they send their slaving raids. Whilst it is the closest part of the Underdark to the surface world, travel there must not be taken lightly as there exist many dangers in the region that are just as deadly to seasoned Underdark explorers and travellers as there are to any novice who might wander into its subterranean depths.

Geography

Of all of the Underdark's levels, the Upper Underdark has by far the most diversity when it comes to the various types of terrain and ecosystem that exist within it. In the north-east, central and south west regions, pockets of lava have made their way up from the depths, creating large lakes of molten rock, immersion in which would result in a near instantaneous, but unimaginably agonising death. These lakes are also surrounded by choking fumes and yet denizens of the Underdark, Duergar in particular, still choose to live near such hazards, using the lava to fuel their forges. Odd areas also exist in the Upper Underdark, where lava once was able to make its way up to this level, but where the lava has long since ceased to flow. In its wake, the lava has left tunnels and caverns of crystalline glass in its wake, which become dazzlingly bright when light is brought within them, and whose smooth surfaces can be incredibly treacherous to an unwary traveller. The south east of the Upper Underdark is a vast expanse of fungal wetland, and fresh water lakes known as the Midnight Marshes, home to all manner of foul creatures, and through which there are said to be hidden passages down to the Middle Underdark below, and the waters of the Lake of Tears. Additional lake systems exist in the Upper Underdark, the largest of which are the Sapphire Lakes in the north west of the region, renowned for the gems that can be found on the lake bottoms and cavern ceilings of the area. In addition, a number of underground rivers flow through the region, which connect the underground lakes of the Upper Underdark in an almost continuous loop. Whilst these rivers provide fresh water for the communities and creatures that choose to set up home nearby them, their fast flowing, incredibly cold waters are extremely dangerous, not just because of the speed of their currents or blood chilling temperature, but also because, just like the underground lakes, they provide homes for predatory denizens beneath their dark surfaces.

Natural Resources

Whilst the Upper Underdark doesn’t have the largest deposits of the most precious gems, crystals and highly desirable rare substances within its bounds, it does statistically have the largest deposits of desirable natural resources out of all of the Underdark's three levels. Rich veins of iron, copper, tin and other base metals can be found, as can veins of silver, gold and precious stones.