What should you do if you forget to set your dive computer's FO2 before a dive?

Proceeding with a dive after forgetting to set your dive computer's FO2 (Fraction of Oxygen) before the dive can still be done safely as long as certain precautions are taken. The key point is that many dive computers default to a standard setting that is often adequate for recreational diving. If you forgot to adjust it for a specific Nitrox mix you intended to use, it's essential to ensure that the mix you are breathing falls within the safety parameters of the default setting.

By continuing the dive, you must remain attentive to your dive profile, depth, and bottom time to monitor your exposure to oxygen and avoid exceeding safe limits. However, while it might be permissible to proceed under certain conditions, it’s generally better practice to make sure all settings are correctly configured before the dive to fully utilize the benefits of using Nitrox, such as enhanced safety and longer bottom times with reduced nitrogen absorption.

Some divers might choose to abort the dive for the sake of safety if they feel uncertain, but the choice to proceed can be made safely if proper precautions and awareness are maintained during the dive.