SDI Open Water Scuba Diver Practice Exam 2026 - Free Scuba Diver Practice Questions and Study Guide

The primary concern when ascending to the surface after a dive is monitoring for nitrogen buildup and preventing decompression sickness. As divers descend, they are exposed to increased pressure, which causes nitrogen to dissolve into their tissues. During the ascent, as the pressure decreases, it is essential to off-gas this nitrogen safely. If a diver ascends too quickly without allowing the dissolved nitrogen to leave their body gradually, it can form bubbles in the bloodstream and tissues, leading to decompression sickness, often referred to as "the bends."

To prevent this, divers typically adhere to a set ascent rate and may include safety stops at certain depths in their ascent plan. This helps reduce the risk of popping bubbles that could lead to serious health issues. Therefore, prioritizing the management of nitrogen buildup is crucial for the safety and well-being of the diver after a dive, making this choice the most important concern during ascent.