Whenever I mention insurance to other divers, ninety percent of time divers are 'already insured through their bank'. Nowadays most banks offer insurance but there are certain pitfalls that can catch some divers out so read the small print carefully, especially if you're renewing as banks can change their terms and conditions so you might not be as covered as you originally thought.
THE SMALL PRINT
Insurance companies can often be slippery to deal with and deny cover for any reason they can find. Their terms and conditions are often 'to your qualification' or a maximum depth, so if you go 10cm deeper than your qualification then they will deny cover right when you need it most. Someone I have known has had a six figure bill for a few hours in a chamber and medical bills which I wouldn't want to pay for without help. And please don't think that you are immune to decompression illness just because you've been on hundreds of dives without a problem, there are so many unpredictable causes of DCIs and other injuries underwater that I'd rather have cover and not need it, than need cover and not have it. Where you are diving and what kind of diving is also a big deal, many insurers have different policies for different regions with higher premiums for diving in more obscure places and God forbid you want to go below 30m! So that expensive trip to Truk Lagoon is now even more expensive than you originally planned as it's outside of EMEA. Now this all makes sense from an insurers position as the price of care can increase the further you go but you do have to double check that you are covered for where you are planning to dive.
For most divers insurance is just for medical bills and lost equipment but professional divers need another level of insurance; legal cover and student cover. Many training agencies like PADI cover instructors with their legal team if a claim arises against their course structure, so as long as you keep to your training agencies course structure you should be fine. Anything outside of the course structure needs cover against possible court cases that are all up to you and students need covering too as new students probably won't have any cover to speak of. If something happens to your student whilst in your care you could need to provide medical care and proper representation if the worst were to happen.
WHO WILL COVER ME?
There are many insurers out there and we live in an age where you can really spend your time shopping around to see who will offer the best deal for you. By all means talk to your bank about cover but just check all of the details as they probably won't have a great deal of expertise in the area of SCUBA so I'd rather look at a company who focus more exclusively with water-sports or simply SCUBA diving. Here at Simply Scuba we work with a company called Divemaster Insurance who offer a free no obligation quote for cover that you can tailor to your needs. They cover a very wide range of adventure sports and have specialist insurance from Bamboo Rafting to Whale Watching with almost everything in between. Another Insurer I can recommend is the Divers Alert Network or DAN. I used DAN professionally for years when I was teaching and thankfully have never needed their services but I knew that whatever the circumstances I was covered for any work that needs covering.