A collision avoidance system for a machine is disclosed. The collision avoidance system has a first obstacle detection system. The first obstacle detection system is configured to detect a first obstacle and generate a corresponding first signal. Additionally, the collision avoidance system has an operator interface. The operator interface has a display configured to communicate visual information to an operator. The operator interface also has an input device configured to receive selections from the operator and generate a corresponding second signal. In addition, the collision avoidance system has a controller. The controller is in communication with the first obstacle detection system and the operator interface. The controller is configured to control the display to provide a first dangerous obstacle warning to the operator, based on the first signal. The controller is also configured to control the display to provide a second dangerous obstacle warning to the operator, based on the first and second signals.