What should a diver do if they suspect inaccuracies in their depth gauge?

When a diver suspects inaccuracies in their depth gauge, the most appropriate action is to follow established procedures for checking and maintaining the equipment. Regular maintenance and checks are critical for ensuring the safety and performance of diving equipment. The recommendation to check the equipment every 18 months aligns with standard practices in the diving community for ensuring that depth gauges and other critical instruments are accurate and functioning properly.

Depth gauges are vital for monitoring how deep a diver is at any given moment, which is crucial for avoiding risks such as decompression sickness. If there are doubts about the gauge's accuracy, relying on a pre-determined maintenance schedule is preferable to ensure that it is thoroughly checked and tested by qualified personnel. This ensures that any discrepancies can be addressed adequately before they lead to unsafe diving practices.

In contrast, options suggesting ignoring the issue or delaying verification may lead to dangerous situations underwater if the gauge fails to provide accurate information. Regular checks, as seen in the other options, are essential but differ in frequency or thoroughness compared to the best practice of every 18 months, which ensures a more rigorous evaluation of the instrument's reliability.