What is the primary purpose of dive tables?

The primary purpose of dive tables is to help plan dives regarding depths and limits. Dive tables are designed to provide essential information about how long a diver can stay at various depths while avoiding decompression sickness (commonly known as "the bends"). By using these tables, divers can determine safe ascent times, surface intervals, and maximum depths for their dives based on the duration of their exposure to water pressure.

The dive tables account for the fact that as a diver descends, the pressure increases, and this affects how nitrogen is absorbed by the body. Without careful planning using dive tables, divers could unknowingly exceed safe limits, which could lead to serious health issues. Therefore, the correct answer emphasizes the primary function of these tools in dive planning, ensuring divers manage their dives safely.

The other choices relate to aspects of diving but do not specifically encapsulate the primary function of dive tables. For instance, while dive tables may provide some theoretical background for divers, that is not their main purpose. Similarly, while underwater navigation is crucial, it is typically managed with tools designed specifically for that function rather than dive tables. Finally, tracking a diver's progress over time is helpful for growth and skill development but is not what dive tables are fundamentally intended for.