On this page of our guide to Death Stranding you will find a solution for the riddle that occurs in Chapter 8: Heartman. You will find out how to get to the other end of the tar belt so that you can continue your journey.
You will encounter the problem of crossing pass the tar belt after completing Order no. 62 (Repair: Chiral Relay). You will be given the task of connecting the Edge Knot City to the network. Do not attempt to enter or drive in the water. Sam cannot swim and after being far away from the shore he will drown.
Follow the shoreline until you reach a place with BTs. Get attention of the monsters so you may be caught and dragged away from the tar by BTs.
The above action is aimed at "transporting" Sam to the tar belt where a creature resembling a whale appears.
Don't fight with the big monster, but use the buildings emerging from the tar to head towards the opposite end of the tank. Remember not to be in the tar too long or Sam will be sucked in. If necessary, stop at smaller objects protruding from the water (for example, on car wrecks).
The destination of the crossing is a spot where Amelie resides. When you get close to her, a new cut-scene will be displayed. You will finish the riddle of passing through the tar belt.