The Tunnel (not to be confused with the maintenance tunnel near the abandoned building) is in Rosswood park. Jay and Alex have taped major events there.
Videos
Below are the videos that feature the tunnel.
Entry #29
Jay finds a video hidden in his hard drive. A camera man with a chestcam runs through the forest, then approaches a tunnel to find a puddle of blood , a bloody rock and a bloody white shirt. The Operator is seen standing at the end of the tunnel.
Entry #48
Jay notices that Alex visits the forest in Rosswood park regularly. He decides to follow Alex in and finds Alex at a tunnel. Jay runs when he thinks Alex notices him.
Entry #49
Alex walks to the tunnel in Rosswood Park. He sits down for fifteen minutes until a passerby asks him if he is okay. Alex shouts, "I told you not to follow me!" and attacks the man. After strangling the man, Alex smashes the man's head with a rock. Later, the Operator appears and then vanishes along with the body.
Entry #50
Jay meets Alex meet at Rosswood Park. Jay follows Alex into the forest, leading up to the events of Entry 38. The footage then continues after the end of Entry 38 when Alex agrees to leave the forest because it is getting dark. Alex tells Jay to bring Jessica next time. As Jay is walking out of the forest, he spots the Masked Man. Jay chases the man to the tunnel but the man disappears.
Decay
Decay includes footage of Alex in the tunnel after killing Bruce. It also includes footage of a forested area, though not neccessarily Rosswood.
Entry #64
Jay and Tim go to Rosswood and search through the warehouse where Alex tried to shoot Jay and Jessica. They continue to the tunnel, where Jay gets a phone call from Alex, stating: "Leave. Now." Quickly afterwards, The Operator appears at the end of the tunnel and debilitates Tim. Jay tries to drag him off, but to no avail. Jay runs away, and goes back to his car. Jay finds Tim there, in his car, but Tim ignores him and drives off.
Display
Display features the tunnel in Rosswood.
Entry #65
Entry #65 chronicles Tim's point of view complementary to Entry #64. He begins in the tunnel and runs through Rosswood. He drives to the hospital, where he seems to be psychologically tortured by the Operator. He makes Jay agree to visit the hospital.