My wife is originally from Cameroon and we are going there on a regular basis. I have shipped a tank and some weights and last time, November 2014, I took all my gear.
To cut a long story short: Cameroon must be the only country with a shoreline without diving. The "dive shop" in Kribi is a (very nice, but unfriendly) "Hotel du Phare" with one french expat doing some kind of diving. When I called them to ask to dive I got the short, but clear answer "Not possible".
It might be easier to dive in the english speaking part, west of Limbe at the "Seme Beach Hotel", which, as far as I know, is close to where the divers of the Cameroon navy (it appears!!) are being trained. On Youtube are some videos of diving in that region from a belgian guy.
If you find out anything new, I would appreciate if you could share.
Patrick