For a complete solution including support from professionals who know the diving industry the best is
http://www.scubapromotion.com they work virtually with customers all around the world. There are located in the middle East in Hurghada Egypt and Switzerland. What I like is that they have many scripts (part of websites) already customized for the diving industry like last minute boards for trips and liveaboards, booking forms and much more.
You can choose to maintain your website yourself or use their professional team from A to Z.
I hope this helps your search.
Mako