Reporter Films Ship Dropping Tires Into the Ocean, Then Learns the Reason Behind It

A Propeller Trap

The diagram showed a cross-section of the underwater channel. Rocky ridges on either side, a deep passage between them. Across the passage floor, accumulated tires formed a dense field of rubber and steel wire.

Any vessel passing through at normal speed would drive directly into it and foul its propeller within seconds. The ship would go dead.