What is one key rule regarding the use of Single-Depth Limits in diving?

The concept of Single-Depth Limits in diving emphasizes that divers must adhere to specific time limits based on the maximum depth reached during a dive. This rule is crucial for managing the risks associated with narcosis and decompression sickness, as increasing depth intensifies these risks. By linking time limits to the maximum depth attained, the protocol ensures that divers do not exceed safe exposure times without proper decompression stops, effectively enhancing safety during the dive.

Understanding these limits helps divers plan their activities more effectively, ensuring they remain within safe operational boundaries throughout their dive. The structured limits are also designed to protect divers from ascending too quickly or spending too long at deeper depths, where physiological stresses are greater.

In contrast, the other options suggest practices that could compromise safety. For instance, allowing multiple excursions between depths might confuse adherence to the depth-time limits and increase risk. Unlimited dive time at any depth contradicts the regulatory framework aimed at managing dive risks safely. Lastly, restricting Single-Depth Limits only to depths below 40 fsw does not reflect the rule’s broader application across various depths, making it critical to recognize that the depth-time relationship is vital regardless of how deep one dives.