In the long term, I hope we see a change in the American tipping system. In the short term, at least make it clear to all whether someone who is providing a customer a service in the US is a tipped employee like a restaurant server. It's clear how the game works for restaurant servers, but not for dive crew. You can be certain that no US restaurant server "works only for tips"--it would simply be illegal. I'll go a step further than Clark and say tipping restaurant servers IS (okay, ALMOST) "mandatory" because their employers are legally allowed to pay "tipped employees" less than what most of us understand is the minimum wage, and if too many people short the server on tips then their employer has to make it up, which they may or may not do properly. Not to get too off topic, but when I get poor service in a restaurant I reluctantly leave the full 20% per the rules of the game and then leave a complaint with management--I think the server still deserves to receive their regular pay at the expected time, just like any of us who make some mistake on the job. But if a deck hand is working "only for tips," what ARE the rules of the game? Is he really more of a volunteer? If so, why should I tip him? Is he covered by labor laws as an employee? What if he's injured on the "job"? If he's a tipped employee like a restaurant server, then I believe I DO need to leave 20%. I think everyone involved--dive op, deck hand, and customer--could be better off if they had a little more certainty as to what's going on. I realize this goes beyond the issue of tipping, but I think it's all related. It's a mess.