What is the second rule from Sheck Exley's Blueprint for Survival?

The second rule from Sheck Exley's Blueprint for Survival emphasizes the importance of following a continuous guideline. This principle ensures that divers have a reliable navigational reference throughout their underwater excursions, particularly in cavern diving where visibility can be limited and the environment can be complex. Following a continuous guideline allows divers to maintain a sense of direction and facilitates a safe exit route, which is critical in emergencies. It supports both safety and effective navigation, enabling divers to avoid the risk of becoming disoriented or lost in intricate underwater environments.

While using multiple light sources, maintaining gas levels, and practicing within limits are indeed essential safety protocols for divers, the specific focus on a continuous guideline directly addresses navigation and the prevention of potential disorientation, making it a foundational aspect of Sheck Exley's recommendations for safe diving practices.