"Farthest west, near the border, is a thick forest area variously called the Riverfork Woods and the Achelos Woods; these woods are largely unexplored, uninhabited by humans (except for the lucky soldiers garrisoned at Riverfork Keep), and very ominous."It would be good to establish some kind of Wandering Monster chart and perhaps some keyed encounters in this area regarding the dangers in these woods. It's likely that they would be occasionally sighted along the riverbanks -- the more intelligent dangers might raid ships or prey on unsuspecting travelers.
"There is one swamp in Karameikos -- Blight Swamp, near the western border. It's not a healthy temperate swamp; rather, it's an ugly landscape of dying trees and rotting vegetation. Disease-bearing mosquitoes infest its still waters and strange creatures glide under the water's surface."You have to pass through Blight Swamp to get from Riverfork Keep to the Black Eagle Barony. Given the ominous nature of the swamp, it's unlikely that night-time passage would be regularly attempted. Like the woods to the north, a Wandering Monster chart and keyed encounter list makes sense and would add to some mysterious sounds and sightings that regular travelers along this route could pass on as rumors. Also, 'bandit raids' from the unscrupulous Black Eagle Baron might plague some regular travelers or high profile targets along this route.
"In western Karameikos, the Rivers Cruth, Magos, Gustos, and Achelos pour down out of the Cruth Mountains. About fifteen miles north of the border of the Black Eagle Barony, they all come together into the greater River Achelos. This river broadens and slows as it passes out of the woody terrain, and drains slowly through the Blight Swamp and out into the Gulf of Halag."Both these locations (Riverfork Keep and Kelvin) should be great sources of rumors from the various wilds in the northeastern corners of the kingdom. If there are river-based inns or communities that benefit from river travel, they should also be home to intersting stories, trinkets, clues, and mysteries from wilderness and mountains. They includes a river that veers near the Lost Valley of the Hutaaka, a river that runs parallel to the Duke's Road, and a river that goes to Castellan Keep (which steels itself against the humanoid tribes on these borderlands), and the Altan Tepes Mountains (which hide gold and Frost Giants).
"In central and eastern Karameikos, the river Windrush comes from the Black Peak Mountains, and the rivers Hillfollow and Highreach come down from the Altan Tepes. They all join together near Kelvin, and continue (as the river Highreach) on to the sea."
"The nation has many, many smaller rivers not shown on the map. Wherever you, for plot or story purposes, need a river or a creek, add it. You can be sure that any city or community which is not shown as being beside a greater river will be near a small body of water."One such location is Koriszegy Keep. Supposedly abandoned and haunted, it should still be located near a river or two -- one that would have provided its inhabitants with fresh water and perhaps reliable travel while it was still a living community. Perhaps intrepid adventurers might see ghost boats along its waters as well -- rumor holds that there is an annual ghostly procession of boats from it to a location filled the lost Korizegy Treasure Caverns...