Fetish

 It's possible for fetish and kink to be a part of swinging. Toys such as vibrators, dildos and strap-ons are often used. Some undergarments and play garments are very erotic and swinging is one place where you are able to publicly wear clothing and other items that you find arousing. Photography can be quite common as well. People enjoy being snapped while they are having sex. 

Fetishes can also be quite personal. They can be very enjoyable even if not part of sex with partners.

One fetish that I have enjoyed over the years is scuba fetish. Like most fetishes it is thought to be associated with childhood and sexual arousal. Scuba fetish videos are quite common and I enjoy vintage scuba especially any that involves twin hose scuba and air supply. I find any air loss, free flowing mouthpieces and regulators, buddy breathing and low air situations to be arousing. When combined with self pleasuring, the end result is very satisfying. There is one episode I enjoy where Mike and a woman swim into a cave. She has swapped his tanks. When he goes in past an obstacle he suddenly runs our of air. Mike checks his emergency but it actually already on. She comes to his rescue bur snags her air hose and pulls the demand side hose off her mouthpiece so that the hose is free flowing. Mike comes back and pushes the hose onto the mouthpiece and they both can buddy breathe but Mike decides to swap regulators underwater so that they can escape. I find it very arousing.