The Kenai River is a simply gorgeous river that flows through the center of the Kenai Peninsula from Kenai Lake to the ocean. It is a world famous fishing destination, but also an extremely fun river to raft or kayak.
At the put in under the cooper landing bridge the river is a brilliant green hue caused by a complete lack of glacial silt (all the silt has sunk to the bottom of the extremely deep Kenai Lake long before the river begins). As you start you have about a mile of swift class I before the first rapid, the class II, sometimes III "Fishermans Bend." This rapid is basically a small drop followed by a fifty yard or so wave train, very easy and fun.
After this rapid, the river continues for three more miles of swift class II until coming to the next major rapid, a 180 degree bend followed by a wave train known as "Schooner Bend."
After Schooner bend you have about four miles of swift class I water until coming to the take out point at the Jims Landing Boat Launch. This section of water is quieter but sports abundant wildlife. I always see moose here and if the salmon are running, there will be bears around.
If you continue past Jims Landing you will run the very fast and fun Class III Kenai Canyon... but there is a problem here. If you run the canyon you must have some form of boat shuttle arranged, as the canyon empties into the 50 plus mile wide Skilak Lake, making it a long, slow, and sometimes dangerous flatwater paddle if you don't have a boat waiting. As a result people rarely run the canyon.
Overall the Cooper Landing to Jims Landing section is an extremely scenic float through the heart of the Kenai peninsula and an easy whitewater float for the beginner.
This is a world famous fishing destination, and as you might expect there are lodges and cabins along the entire route. There are stores in Cooper Landing that provide shuttle services, showers, and any rafting/kayaking equipment you might need. If you are looking for a larger hotel you will probably have to proceed 30 miles south to Seward or east to Homer.
There is a five dollar parking fee at the put in. If you wish to use a paid shuttle service to drive your car to the take out point, it is normally about 30 dollars.
From Anchorage, proceed south on the Seward Highway for 98 miles until coming to the junction of the Seward and Sterling highways. Take the Sterling Highway west and proceed on it for six miles until coming to the town of Coopers Landing.
There is a very nice boat launch built under the Kenai River bridge in the town of Coopers Landing. The take out at Jims Landing is also a built up boat launch, very easy to use and hard to miss.
If you want a slightly shorter run you could also take out at the Russian River ferry site, which is about a mile after the Schooner bend rapid (you can't miss it).
Karen Jettmar's "Alaska River Guide" provides a good description of the Kenai River.