Kayakers on the Green River between Dennison Ferry and Green River Ferry in Mammoth Cave National Park

Length: 7.9 miles
Water Level at Time of Trip: 8.35 feet
Average Moving Speed:  2.6 MPH with two paddlers
Top Speed:  5 MPH
Time: 3 to 4 hours

GENERAL INFORMATION

This paddling review covers a trip on the Green River within Mammoth Cave National Park starting at the Dennison Ferry Day Use Area and ending at the Green River Ferry (the Green River flows east to west). Both have canoe launches that require carrying boats down / up stairs, for the parking areas are high above the river. Both launches do, however, have a slide for boats that makes getting down easy, and getting up easier than the alternative. The slide at Dennison Ferry isn’t as nice as the one at the Green River Ferry. The wood is a little rough. The outer layer of the bottom of my friend’s inflatable kayak got ripped while sliding it down the ramp, though it did not puncture the air chamber. It’s not a problem for plastic or fiberglass boats, but those with inflatables might just want to carry their boat down the stairs if the wood hasn’t been replaced.

Boat slide at the Green River Ferry Canoe Launch, Mammoth Cave National Park

Boat slide at the Dennison Ferry Canoe Launch in Mammoth Cave National Park

Those who want to paddle the entire Green River within Mammoth Cave National Park must start their trip outside of the park boundary because the first boat ramp within the park, Dennison Ferry Canoe Launch, is approximately three miles west of the eastern park boundary. The closest public boat launch that I know of in that direction is miles away in Munfordville. Thus, Dennison Ferry is where nearly everyone starts a river trip within the park.

Kayakers on the Green River departing from Dennison Ferry, Mammoth Cave National Park

THE FINE PRINT

Before starting a river trip through Mammoth Cave National Park, it is a good idea to check the water levels so you have an idea of the river conditions. The United States Geological Survey (USGS) water level gauge within the park is at the Green River Ferry. This is the gauge used by the National Park Service to assess conditions. However, understand that water level gauges only measure water depth at one location and that the actual depth of the river varies from place to place. For example, if the Green River Ferry gauge reads 8 feet, it would seem impossible to get stuck on the bottom because eight feet is way more water than needed for canoeing and kayaking. However, an 8-foot reading at the Green River Ferry may mean that some areas of the river have only six inches of water. Using this ratio, if the USGS gauge reads 10 feet, then the shallow areas would have two more feet of water, which is plenty for canoeing and kayaking.

I did the trip when water levels were 8.35 feet per the USGS gauge, and when I checked a year’s worth of historical data, this is as low as the Green River gets. When I asked a park Ranger about conditions the day before my trip, he was worried if there was enough water to make it down the river. There was. I had to get out and pull my boat through shallow water a few times, but this wasn’t a big deal. This may well have been due to not being in the deepest channel to begin with. Those who know the river like the back of their hand might not have gotten stuck.

Shallow water on the Green River near Cave Island, Mammoth Cave National Park

Per the National Park Service, water levels between 9 and 15 feet are suitable for all paddlers. At these levels, the Green River is mainly calm with some choppy water here and there to spice things up a bit, but nothing even first-time paddlers couldn’t handle. In fact, I wouldn’t hesitate to bring along a small child who could swim, if I had a small child who could swim (of course the child would have on a life jacket). Be aware that regardless of water levels, extreme winds can cause turbulent conditions that require advanced skills on water otherwise suited for all paddlers.

The National Park Service further states that water levels from 15 to 18 feet are for intermediate paddlers, and levels between 18 and 20 feet require advanced skills. The canoe launches within the park are closed due to safety concerns when levels are over 20 feet.

RIVER TRIP DETAILS

When the water levels are as low as they were when I did the trip down the Green River, the river is like a lake with barely any current. I could paddle upriver just about as easily as downriver. I measured my speed when floating and got readings as low as .6 MPH. Despite this, I paddled the first mile in 20 minutes (3 MPH) in a two seat high-end inflatable kayak. My wife was paddling with me, and she is a beginner. With my daughter and her friend in another inflatable—first time for both of them—we completed the Dennison Ferry to Green River Ferry trip in 4 hours, which included 30 minutes worth of stops. Any family should be able to complete the trip in this amount of time. Athletes who paddle nonstop can do the trip in as little as 2 hours, and certainly within 3 hours.

Calm water on the Green River three miles downriver of Dennison Ferry, Mammoth Cave National Park

Kayakers on the calm waters of the Green River 1.3 miles downriver from Dennison Ferry, Mammoth Cave National Park

Based on the National Park Service’s claim that water levels between 9 and 15 feet are appropriate for paddlers of all skills, what I experienced at low water levels should be similar to any trips taken during these conditions. As mentioned, 99 percent of the trip was on calm water, and short sections of minor riffles were about as exciting as things got. The higher the water, the faster the current and the more sections of turbulent water, which is what most people desire on a river trip. Thus, expect a more enjoyable trip when levels approach 15 feet than when they are at 9 feet.

Choppy water on the Green River between Dennison Ferry and the Green River Ferry at Mammoth Cave National Park

Turbulent water tends to come when the river channel narrows, typically when splitting in two to go around an island. This is due to a large amount of water suddenly being squeezed into a smaller space. However, I can’t give details about where the islands are and suggestions on how you should go around them (left or right side) because the islands I encountered may well not be there when there is more water in the river. I noticed this when searching for the island locations on Google Earth (satellite imagery). The islands I encountered weren’t there on the most current image. However, when I went back in time through the images, they appeared and disappeared. Most of the islands I went past weren’t but a couple feet above water when the USGS gauge reported 8.35 feet, so at 12 feet or more they would be underwater and would not show up on a satellite image taken at that time.

Narrow channel around an island on the Green River halfway between Dennison Ferry and the Green River Ferry, Mammoth Cave National Park

Narrow channel at the downriver end of Floating Mill Island a mile upriver from the Green River Ferry, Mammoth Cave National Park

The National Park Service uses the 9-foot number as its low-end figure for an enjoyable trip down the Green River. However, I have no major complaints about my trip when the USGS gauge read 8.3 feet, but I certainly wouldn’t go with less water, perhaps using 8 feet as the absolute cutoff point for a paddling trip. I got stuck on the bottom three times, but once was at an island near the halfway point, and everyone was ready to take a snack break anyway (I knew it was shallow when I saw deer standing barely hoof-deep in the water). Regardless, it wasn’t a big deal to get out a couple of times and drag the boat a short distance to deeper water.

Island near the halfway point on a Green River trip between Dennison Ferry and the Green River Ferry, Mammoth Cave National Park

As for breaks, the best place to stop is on an island, as the shore of the Green River tends to be covered in vegetation. There was a place to stop only a mile downriver from Dennison Ferry that, per the Google satellite images, is accessible most of the time. The other stop we made was near the halfway point (3.5 miles into the trip) on an island that also should be accessible most of the time.

Island beach along the Green River a mile downriver from Dennison Ferry, Mammoth Cave National Park

Island beach at the halfway point on a Green River paddling trip between Dennison Ferry and the Green River Ferry, Mammoth Cave National Park

The only other landmark worth mentioning is a cave shelter a half mile from Dennison Ferry. You can paddle over to it provided the water isn’t too high—the cave would be hidden underwater. You can’t paddle into it, but you can get close enough for a good look.

Cave shelter on the shore of the Green River a half mile downriver from Dennison Ferry, Mammoth Cave National Park

About three quarters of a mile before the Green River Ferry is Cave Island. If you hiked the Green River Bluffs Trail or the River Styx Spring Trail, you may have taken the overgrown detour to the Old Riverboat Landing. As you paddle down the river and suddenly see people standing along the shore at what seems to be in the middle of nowhere, that’s the landing.

View of the Green River near the southwestern end of the Green River Bluffs Trail, Mammoth Cave National Park

The Green River Ferry Canoe Launch comes before the actual Green River Ferry, which wasn’t operating due to low water when I made the trip. The canoe launch is on the left—you can’t miss it.

Green River Ferry Canoe Launch in Mammoth Cave National Park

View of the Green River Ferry from the Green River Ferry Canoe Launch, Mammoth Cave National Park

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