What use of social networking for a scuba diving equipment niche can be effective?

What I want to do is sell scuba diving equipment. I could consider getting into promotion of vacations related to scuba diving. As I go along and get some kind of traffic I am sure to come up with new directions to follow with my website. Maybe I will create some new sites and/or promote WA.

To date my posts describe and discuss and review equipment. I am promoting some more technical equipment and have one post related to wreck salvage and will do more related to commercial diving, gold dredging and salvage that are not just discussions of equipment, but involve a little history and story telling. I would like to generate commentary from readers, but I suspect it is not a subject that will develop a lot of feedback.

As required by the training here I am enrolled on Facebook, twitter, google+ and pinterest. I have lived in Asia for the last 32 years. A lot of the time I did not have internet access and there was a stretch in the 90s in the Philippines with no telephone or TV (or electricity or clean water) and recently with google, Facebook and others blocked here in China. Until the last couple of years there wasn't a reliable vpn available here. The point of this history recitation is that I do not have a big historical social network to draw upon. There are social platforms in China that are very effective here, but are heavily monitored by the government. I am leaving China in another month and don't plan to maintain contact with people here.

Facebook doesn't seem like a platform to share my website with. Sharing there just seems like spamming. I suppose it is the same with google+. I can easily generate followers at pinterest. It remains to be seen if traffic will come from that, but I feel somewhat hopeful there. At twitter, generating followers is slow going, and again what I write about regarding diving just doesn't seem to be a subject for that platform. Of all the people who have emailed me at all my addresses over the years, not one is on twitter.

Where is my thinking and approach right or wrong? I'd welcome any ideas.

Thanks.