This is level 5 of The River.
In this level, there are no tricks that can actually help you. Follow the path of the spiral, and you can just run all the way on the boxes. This level is very easy, and we recommend using the Runner since she moves sideways better than the Skater, giving her an edge of beating this level.
The much more fun way is with the Child. You get blocked by a box, move sideways until there are no more cyan tiles, go left, and you'll find yourself a long, long way up. Jump now, and it should be enough to pass through the entire level. Aim for the platforms if you don't reach the end with the mega-jump.
Since this is the end of the F-tunnel (or The River), therefore you will see a void in front of you when you are about to beat this level. Feel free to jump in it! You will then initiate a cutscene.
Here is a brief description of the cutscene featuring in this level. More can be seen here.
Socratic Method Edit
After beating F-5, the Runner agrees to let the Child name the F-Tunnel. Then the Child suggests to move the A-tunnel towards the Box Storage Area tunnel. But the Runner says it is not there and the Child says the map is lying. Then he changes the name F-Tunnel into the River.
After this cutscene the F-tunnel will be changed into the River.