Thanks for all the replies. I decided to send an email to the guy who runs the shop Against the Grain Wood Studio, which is who i was going to buy them from. I'm going to post his response in case anyone else ever runs in to this problem.
Thank you for your question. First of all I've been snorkeling but never scuba diving, so I admire you for having that as a job, that must be amazing. Wooden plugs are recommend to be taken out before getting wet, due to the fact that wood is porous, and even though the wood is technically dead, the grain in the wood main purpose was to transfer water from the roots up to the limbs, and leaves. So when water comes in contact with wood, the wood grain pores naturally absorbs the water causing the wood to swell. The wood will swell on the side grain, and not so much the end grain, so what will happen is that your gauged ear will get alittle more stretch as the wood swells. Now because every wood has a different reaction to water, it is just totally recommend to take the plugs out before getting wet so you don't run into any complications. I am not recommending it, but I do know quite a bit of people who do leave their wooden plugs in during showers, and have no problem with it. Also the size of the plug has alot to do with how much the wood will swell. The smaller the size the less swelling, the larger the plug size the more swelling. Also I would recommend using solid plugs. For our inlays, stripes, and Xs we hand laminate them with water proof wood glue, and the glue joint is actually stronger than the wood itself, but because of wood being laminated up, the grains are now running in different directions, when they begin to swell the woods will actually tear each other apart. So If you would decide to wear wooden plugs while diving, it would be under your full understanding of risk. For your purposes you would want a tight grain wood like Bloodwood, Purpleheart, Ebony, instead of a very open grain wood like Oak, or Palmwood. So if you want to send me an e-mail back telling me your ear size, and types of woods you are interested in, and I can let you know what will possibly happen with that type of wood, while diving. Also I have never heard of salt having any special reaction with wood, except for a slight color change in the wood. And waxing the plug regularly, will dramatically decrease the risk of or swelling of the wood, because of the fact the wax is used to help seal these pores in the wood grain, absorbing less moisture. I hope I answered all of your questions, if you have any more i would be delighted to answer them. Take care, and watch out for them sharks, while diving.