Being a fellow Open Water Rescue Scuba Diver and avid year-round diver, I think you got some great ideas below. Incorporating some videos might help as well as reviews of equipment, best times of year to dive certain sites, cheap places to dive, etc.

Mark

Have a look at the scuba adverts on google or Tv ads and get a good idea on what to write as a post

Hi Shawn, I don't know your niche very well but I did take a Scuba Diving Open Water 1 course when I was still in High School. Perhaps you could add some blog posts on what courses to take and what you learn on each course?
You could also do a post on where to find courses.
I also recommend finding other diving websites, you'll get a lot of ideas from them. Don't copy them, just for ideas for posts.
Another really easy way to get more posts is to interview divers. You've listed the various types of Divers. Why not try get an interview with each one so eventually that list will contain links to each of your interviews.
The interviews will give you loads more ideas for more posts.
Then you're going to want to offer reviews on diving equipment because that's where you can start generating some revenue.
You could write about safety... scariest dives you've gone on, The Bends and how to avoid it.
You could write about diving in the news - remember that terrible diving accident last year in Thailand, when that Teacher took School kids out to see a cave and the tide came in and they were trapped? 1 Navy Seal died trying to rescue them but eventually all the children and the Teacher were saved. It was a really gripping story, the world was waiting with bated breath to see whether the children would all make it out. You can easily add a YouTube video to that one.
Hope that helps. Happy writing.

Just a gentle reminder we cannot add links in our blogs. It is best if you go to site feedback in your profile menu under sites. Here you can request a feedback, but only after you have paid if forward by giving a feedback to two other member's sites. I wish you the best :)

Just a suggestion, but perhaps you could write some feature on the scuba diving sites you have listed. You could incorporate a recommended hotel to stay in at each resort, affiliate linked of course!
That’s all that comes to mind at the moment but I’m sure you will get some more suggestions.
Hope this helps,
Steve.

How about some reviews on different types of dive equipment? Diving for beginners, The best places to dive, What to look for in a dive instructor.

I hope that helps.
Stay positive it will all work out
Be Blessed

Site looks good, did not check each blog but have you anything on the lines of..
Why Scuba Dive
Do you like to Scuba Dive
What is Scuba Diving
Is it expensive to Scuba Dive.

Just a few ideas to pop into keyword research and you should have some blog content hope this helps, no nothing about Scuba Diving except it is under water and I suspect could be very dangerous.
Regards
Stuart