Between The Ridges
There is relatively low ground between the Dungeons ridge and the other two ridges on either side of it and this lower ground passes through the whole hill area from north to south forming two corridors through the hills.
However, the surface of the highest loch in the corridor to the west of the Dungeons, Loch Enoch, is actually around 490 metres above sea level. With Loch Trool being about 70 metres above sea level you can see that this corridor rises significantly as it passes (over a distance of some 5 kilometres) between the hills on either side.
The surface of Dry Loch of the Dungeon the highest loch to the east of the Dungeons is around 330 metres above sea level and most of the Silver Flowe immediately to the south of it lies fairly level at about the 270 metres mark all the way back south to Loch Dee (around 225 metres above sea level). The explanation for this is that the Silver Flowe is a floating or blanket bog and is consequently flat in nature.
Read more about this topic: Galloway Hills