A couple of suggestions from a fellow newbie (just bought mine in late December and used on my first dive trip in Roatan a few weeks ago).
This is a helpful article from Backscatter. Obviously they lean towards buying their filters and a lighting set-up, but still helpful advice regarding settings, what memory cards work best, etc.
Underwater Camera Articles: A Guide to Using the GoPro Hero3 / Hero3+ Underwater
Some more recommendations from personal experience:
- Use the camera a few times before you go, either in or out of the water. Depending on what package you buy, it will come with all types of accessories. You'll find that you don't need to bring most of these on a dive trip.
- Head or chest mount - it really depends on what you want to use it for. I used a chest mount in Costa Rica for zip lining and white water rafting and it was great......activities where you needed your hands free for doing other things....and where I knew I would get some cool footage without having to aim/focus on specific things. For diving where you likely want to focus in on specific critters.....using chest/head mount will give you some interesting footage and probably a lot of throwaway footage. This is personal preference - when I put together a video from diving, I tend to include lots of short clips on the key highlights of the weekend or the trip vs. just recording and sharing entire dives. Also depends on the diving (searching for small critters where action/shooting is more occasional...or a big action shark/manta dive where static might work better, etc.)
- If going hand-held, you'll be happier if you have some sort of mount - pistol grip, pole or tray or some type. Better for control, stability, etc. You will also need some sort of lanyard/leash/clip set-up
- Extra batteries...the number of which depends on the logistics of your trip, how many dives you expect to do per day, time between dives (do you have time to charge, etc.) and whether you want the camera available for every dive. On my recent trip we were doing 5 dives/day (morning boat trip for 2 dives, afternoon boat trip for 2 dives and night dive) - I brought 4 GoPro batteries on the trip, as I wanted to have the ability to use the camera on every dive. I was going through 1 battery per dive as I was using the add-on back-pack display/viewfinder, which is a battery hog....I assume you may get multiple dives out of 1 battery without the viewfinder. So I would have a fully charged battery in the camera for morning dive 1, an extra to change out for dive 2. In the afternoon I would charge the morning batteries and take 2 fully charged batteries on the boat. In addition to the batteries, I bought the separate GoPro battery charger, that let's you charge 2 batteries at once without having to use the camera for charging.
- Filter = really helps with the results. I bought the Backscatter 3.1 flip system and used it on my recent trip - easy and really helped the results.
- Back-pack display = obviously really helpful if you are intent on focusing on specific critters and/or framing shots (video or still). If you want to view video you've shot while on your trip, you can use it for that. Cons are another $80 and it is a battery hog. Obviously you don't need it if you are just using static chest or head mount. The backpack requires using a different housing door (I think this comes with most packages with the Hero 3+), since the housing needs to be bigger to accommodate the slightly added bulk of the backpack.
- Moisture absorption packs = some folks don't use these in warmer climes; that said, there will be moisture around, particularly if you are changing batteries on a rocking boat and the housing isn't fully dried out between dives. I use 1 on every dive (I would re-use over multiple dives unless they were getting saturated)....maybe overly conservative, but my choice.
- Light(s) = this is the most expensive of the add-ons, but along with the filter will be the add-on that will enable you to get the most color correct and clear footage when shooting things in the 0-10 foot range. If you plan on doing night dives, a decent video light can also serve as your primary light...and when mounted on a tray with the camera allows better control, light aim and keeps at least one hand free when you need it. I used this set-up from Sea Life - works pretty well. I brought an extra rechargeable battery for the video light as well...was able to get 2 dives per battery.
http://www.sealife-cameras.com/accessories/sea-dragon-1200
- Memory cards - read the Backscatter article above for recommendations.
- Something for cleaning the camera lens and housing view port - microfiber cloth or lens cleaner.
Hope this helps.
Chris