SDI Open Water Scuba Diver Practice Exam 2025 – Complete Test Prep

The primary function of dive tables is to plan safe ascent rates. Dive tables are essential tools used by divers to manage the amount of time spent at various depths during a dive, ensuring that they ascend at a rate that minimizes the risk of decompression sickness, commonly known as "the bends." These tables provide valuable information on no-decompression limits, which indicate the maximum time a diver can spend at a certain depth without having to make a decompression stop during ascent.

By following the guidelines outlined in dive tables, divers can effectively manage their exposure to pressure changes and help reduce their risk of nitrogen buildup in the body. This planning is crucial for maintaining safety during diving excursions, ensuring that divers can ascend slowly and safely according to the depths they have reached and the duration of their stay underwater.

In contrast, the other options do not align with the primary function of dive tables. Estimating underwater visibility pertains to environmental conditions rather than dive planning, determining water temperature and measuring wave heights are aspects related to conditions above or on the surface but do not address safe diving practices.