Introduction
The River (F-Tunnel) is a tunnel in Run 3: Explore Mode. It is unlocked after completing the M-Tunnel.
Once the Bridge Building side-quest is activated, one of the boxes can be found in The River, part 3.
Suggested Characters: 
Plot
There are two cutscenes in this tunnel. More information can be found on the Story page.
Insanity
After beating Level M-5, a cutscene will begin in which the Duplicator is watching the Runner's attempts to reach a tunnel in the distance. She kept trying, but she fell short every time. The Duplicator asks the Runner if she has gone insane, but the Runner denies it. When she respawns, the Runner notices that the Duplicator drew on her map. The Duplicator says that this is to "commemorate the moment" she has gone insane before the Runner finally makes it past the gap and reaches the F-Tunnel.
Socratic Method
After beating F-5, the cutscene 'Socratic Method" will begin, in which the Runner agrees to let the Child change the name of the F-tunnel, but nothing else. She goes on to explain why, showing him that if, for example, she moved the position of level A-1 to the end of the Box Storage Area, the map would be wrong because there's nothing there. The Child understands, so the Runner allows him to change the name from "F-Tunnel" to "The River". After this cutscene, the F-Tunnel is changed to "The River" on the map.
Trivia
- All the levels in The River were made by Precarious, who originally named the level set "Riptide River Rapids". They were implemented into the main story sometime in March 2015.
- There is an old cutscene that used to be in this level. More about this can be found here.
- This is one of the tunnels where all the levels are colored in any shade or tint of a specific color. The River here has levels all colored in shades and tints of blue(as the Child said that this tunnel is a thin blue line in space). The same thing applies to other tunnels such as brown levels in W-Tunnel and Not the Way Back and green levels in the New Tunnel.
Difficulty
| Sandbox |
|---|
| Very easy |
| Easy |
| Not too easy |
| Almost medium |
| Medium |
| Over medium |
| Above medium |
| Fairly hard |
| Hard |
| Extra hard |
| Insanely hard |
| Hell |
Difficulty of the Levels of The River (F-Tunnel)
| 1 | 2 | 1 | 1 |
