The Kimle Run

The Kimle Run is a section of the Paradon River , generally defined as the narrow area between the ancient cities of Kimle  and Meshen plus several hundred yards north and south of the cities.
This section of the river is treacherous to navigation, from both directions, and has caused a number of shipwrecks. Over time, these wrecks have only added to the difficulty traversing it.
For hundreds of years, the Kimle Run has become a romantic symbol of nautical prowess, personal courage and futility. To date, none have successfully passed through the Kimle Run, or at least not without significant damage to life and ship.

Geography

The current of the Paradon River runs from north to south at an average of 1.2 mph, although in the stretch known as the Kimle Run, the speed varies greatly on the individual section and can go as high as 3 mph.
The Run unofficially begins in a "ship graveyard," several hundred yards south of the cities, continue past the cities on the east and west, across a stretch of jagged rocks at the northern city edge and finally past a pair of large eddys 500 yards north of the cities. There are no significant navigational hazards in the river north or south of the Kimle Run.
There are four main navigation hazards that make up the Kimle Run. Some are natural obstacles that were created due to magical intervention, others are artificial and the results of years of human misadventure and destruction.
The four sections are (from south to north):

1) Shipwreck Half-Mile

Many wrecked hulks of ships that unsuccessfully tried to make the Kimle Run litter the water about 1000 yards south of the twin cities. At some point many decades before now, a fleet of ships attempted to bull their way through the Kimle Run from the south. A great series of miscalculations and lack of cohesion and cooperation among the crews doomed the effort before it even started. The already-hazardous navigational challenges of the Kimle Run were actually extended to the south. 
It is rumored that some of the mariners who perished in this first attempt, as well as some from subsquent attempts, still lurk in and amongst the shipwreck ruins as undead opponents to others who attempt passage.

2) Moon Chute

The channel is narrows greatly as the Paradon passes between Meshen and Kimle. Massive amount of wreckage can be seen spilling into the water from either side. Buildings, structures, trees, towers - all manner and sorts of debris crowd the riverbanks, overflowing the ruined dock areas, and stacking up in the water on either shore.
The water between the cities ebbs and swells, causing the debris to slam into each other in the middle of the river. Many pieces of debris remain to cause navigation hazards. A ship hoping to pass through must constantly anticipate the flow of the debris and pick and choose the safest path, which may change at any moment.
The unpredictable movement of the debris here causes the water to "churn" and change directions/speeds rapidly and without warning.
Some of the new, feral inhabitants of the abandoned cities sometimes lurk in the debris, waiting to pounce upon those who have made it to this point. 

3) Table Saw

As the river emerges from the clashing debris field of the first half of the city, the lateral motion of the water stabilizes, but the chop increases. Numerous sharp rocks and boulders can be seen sticking up out of the water, threatening to cause a nasty gash in the hull of any ship that strays too close...
Alternating sections of treacherous rocks must be navigated with pinpoint-accuracy to safely make it past.

3A) Giant's Breath

A short stretch after Table Saw sees calm waters and easy navigation for app. 100-200 yards. This respite does not last long, but can allow captains to take stock of their situations and make quick repairs before the final obstacle. Seasoned sailors will realize their momentum eventually inexplicably drawn them forward against the current, and to the west.

4) Double Suck

The reason for the odd movement can soon be seen: Two, side-by-side massive whirpools, known as Double Suck, or The Maelstroms, are turning in different directions: Left Maelstrom is turning clockwise, Right Maelstrom is turning counter-clockwise. Ships must navigate around both Maelstroms in a figure-eight pattern to get past, regardless of their original direction.
There are frightening stories of something living inside the Maelstroms, snatching at ships as they pass by.

Passage through the Kimle Run from north to south encounters the same obstacles, in reverse order. Giant's Breath must be fought against coming from the north, due to the pull of the Maelstroms.

Ecosystem

While no larger predatory river species are native to the Kimle Run section of the Paradon River there are stories of some kind of creature living within the dual eddys that has been rumored to snatch men off of passing ships and devour them. Descriptions of a kraken, squid or octopus-type creature are most often reported due to sightings of long tentacle-like arms, but normal varieties of these creatures do not inhabit fresh water so their presence is doubtful. It is entirely possible a different type of similar creature has evolved to thrive in a freshwater environment, but it is as of yet undocumented.
There are numerous river fish that make their homes in the various obstacles of the Kimle Run such as trout, salmon, bass and catfish. Otters, beavers and other small carniverous mammals also make their homes here, and very rarely a manatee will wander south from warmer climates to the north.

Climate

The climate of the Kimle/Meshen region is temperate and the water rarely freezes.

History

In the days before The Elemental Sundering, the twin cities of Meshen and Kimle  thrived as centers of culture and commerce over the Southern region if the Krylan Coalition. After the upheaval, on the heels of the fall of the city of Kryla, Meshen and Kimle were abandoned and fell into disrepair. Conflict between rival factions and magics that reshaped the land and water created a natural and artificial barrier to river travel up and down the Paradon River.
Where once a thriving river trade route existed, today is a treacherous ruin of shipwrecks, city debris, sharp rocks and whirlpools.

Tourism

"Making the Kimle Run" has become a romantic and popular, yet distant and unattainable goal for river mariners over the centuries. The lure of resuming trade between north and south is attractive but no factions have been able to work together successfully to make plans to clear the way and resume something like normal travel.
Only the bravest sailors (or the most foolhardy) with the stoutest river vessels and crews with the stoutest of hearts ever attempt the Kimle Run, with the promise of fortune and glory to those who ever make it successfully through.
To date, none have and lived to tell the tale.

Location under

Paradon River