What does "no-decompression limit" (NDL) refer to in diving?

The term "no-decompression limit" (NDL) specifically refers to the maximum time a diver can spend at a particular depth before needing to perform mandatory safety stops during ascent. If a diver exceeds this limit, they enter a zone where they would need to make stops to allow nitrogen absorbed by the body to safely off-gas, thereby reducing the risk of decompression sickness.

By adhering to the NDL, divers can ascend directly to the surface without the complications of stopping at predetermined depths to allow for safe nitrogen release. This concept is crucial for ensuring divers’ safety, as it indicates the time they can remain at various depths without exceeding physiological limits that could lead to potential health issues.

The other options address different aspects of diving that do not relate to the NDL. For example, while depth limits and ascent times are important, they do not define the no-decompression limit itself. Similarly, water temperature can influence diving conditions, but it does not have a direct connection to the concept of NDL. Understanding the NDL is essential for planning dives, especially when considering time limits and managing risks associated with depth and nitrogen absorption.