bfisher
Contributor
Nitrox isn't the only reason why you might need to show a specialty card. Drysuit rental, ice diving equipment rental, scooter rental, and other such things may require you to show a card too.
No doubt there are situations that require certain cards, such as Nitrox. I have a Nitrox card myself. The card proves I got the training, but Enriched Air is not the same as say,, Boat Specialty.
Many of us do dives from boats. But you don't need to take a specialty course to learn how to get off and on a boat---and use proper etiquite while on the boat. If you get into Photography you don't need a card to be able to take pictures. You don't need a card to go on night dives.
Get my drift? These are a couple of examples of dives you just do. You just learn by doing in many cases. Paying good money to get a piece of plastic is just not necessary.
Peak performance bouyancy is a good example. Pay the shop for the book, read the book and do the reviews, jump in a pool for a couple dives. You aren't going to get it. The only way to get good at bouancy is to jump into the water and work it out. The more you do it the more you relax and the better your bouyancy gets. And it does take time. So how did paying for it help?
I should mention that I'm talking about most of the Specialties listed under PADI recreational diving guidelines. I saw mention of cave and cavern diving and a couple others. These are not common speicalties. They lean more toward technical diving. This stuff does require proper training.