Many people are understandably concerned about the length of time their scuba certifications will remain valid for? A question that comes up often is “How long does scuba certification last?” The broad answer is no, your scuba certification does not expire. This does vary largely according to the certifying agency for your course and that it's always a good idea to refresh your skills when it comes to keeping yourself and your dive partners safe in the water. True safety lies with gaining new knowledge even if you are comfortable using what you already know.
Although your PADI certification does not actually expire if you haven't been diving in the last 12 months (or can't remember how long it has been!), it's highly recommended that you re-train via the PADI ReActivate program. The PADI reactivate program works for no matter what agency you were originally certified by.
During your PADI reactivate, you will only need to fill in the gaps in your current knowledge. You will refresh what you need to either online or using a PC or tablet at your own pace. You will then go back to the pool with your PADI instructor to review the necessary scuba skills. If you are eager, there’s an optional open water dive where you can regain even more confidence.
If you haven’t been diving for quite some time, chances are you have forgotten about your PADI Dive Card. Not to stress, however, because those who undertake both the knowledge and in-water portions of PADI’s ReActivation course obtain a new card with a ReActivation date, thereby enabling dive centres around the world to see how much time you have dedicated to refreshing your own skills.
If you only did your original open water course dives and it has been a long time since you did your original open water course, you may find it better to redo the entire open water course again as much may have changed since you originally learned to dive. Spending the extra time will further help you build your confidence and increase your long-term diving enjoyment.