A great weekend trip. Perfect for beginers to the whole canoe or kayak deal on a 5 -6 mile an hour current...perhaps a class four rapid by Rocky ford or class 6 depending on the time of year. Portage that one unless it's late june or after, then you still take your chances.  Best to wear a hat. I didn't and the two kayakers in front of me spilled, I got lucky. Go at it from the left. The right looks easier but has a severe drop off. Go at it from the left. Stop to study. From the left you will be swept in and then must make a hard right, but not to hard.  The current will pull you away from the cliff before crashing into it. if you go right to hard you will get to sideways b4 the hydrolic and spill. I got sideways but was lucky and rode it out, but did swallow some water. Thank God I wore my skirt. LOL!!!!!!!
About the Niobrara you can find it on Nebraskaoutback.com  It has a beautify nature park at the start with some rules posted. No beer here for the partying crowd. The rangers watch from the high bluffs. Those of us seeking solitude are best to start early. After the park you can purchase beer at stops along the river if you care. For me, I'd rather wait. Booze and boats don't mix. It is a beautiful park and river in that it is the only place in the U.S. that has trees from all 4 forests of the nation and all in one place, but each in their own destinct section. Some looks like the West or the Black hills, Some the South, Some the East and some the ........well our spot....the North. Sandy soil,clean clear water, shallow too. Over 100 waterfalls within 25 miles. Lots of areas to hike. it is cool.  Best outfitter is RockyFord.  Best camp spots... Rocky Ford  ....Rocky Ford... the car not the barn...if you explore, you'll understand.
I would go again.... 

You are welcome.  I hope you enjoy your journey. Journey with us.