Reader Marwah asks,
"I wanted to know if you know of paints or markers or other mediums I can use on my gear that wouldn't be harmful to the coral or marine life. I want to put elaborate, colourful stuff on my fins to begin with but I don't want to do it at the expense of underwater life. If you know of anything I could use please let me know."
Great question! Fortunately, these days paints and markers are fairly safe for the environment and getting better every year. The main things you want to avoid are:
Lead-based paints. These are getting harder to find, but just like its toxic to humans, lead paint in the water can be harmful to sea critters.
Anti-fouling paints. Again, you aren't likely to find these at a local crafts store, but anti-fouling paints are used for painting the hulls of ships. They are designed to kill barnacles, algae, and other marine organisms that would slowly eat away at boat bottoms, so they are of course not good for anything living in the water. I doubt you would run across these, but I don't want readers to see them, see that they are intended for boats and think they are a good choice for equipment decoration.
When looking for paints, one of the key things you need is for it not to be water-soluble, otherwise it will dissolve into the water. Your best bets for decorating are the old standbys:
Acrylic paint is actually a good option, with one caveat: it must stay on the material you paint! I personally found out that acrylic paint (at least the "beading" squirt bottle kind) does not hold well to fins, and will easily get knocked off. Because acrylic paint is just a form of plastic, this can't be great for whatever it lands on. However, it will stick well to BCD's and possibly wetsuits as long as you spread it flat, and it's not any worse for the environment that any other plastic on your BCD, regulator, mask. etc.
If you are unsure, test it out by painting the equipment, let it dry, and knock it around a bit to simulate a dive. If some of it chips off, then you probably should peel off the rest and use something else.
Tip: many scuba shops sell pricey paint specifically for dive gear. This is just acrylic paint, sometimes called "fabric paint", that you can find at any hobby / craft store for one-fourth the price.
Permanent markers are awesome for drawing patterns and coloring. They are not water-soluble and will not leak toxins into the reef. Better yet, permanent markers can write on just about anything, even fins, which acrylic can't hold on to. I personally use them to write my name / initials on my gear.
Update: another email from Marwah alerted me to this option.
Paint markers are oil-based and will soak into a lot of materials that acrylic and permanent markers may not penetrate. In fact, if I were to decorate equipment from scratch, I would buy a small set of paint markers and supplement with a few permanent markers that I have on hand.