i wanted to chime in with my experience in southeast asia and general philosophy.
the Pros here make very little money and the prices are very cheap for us divers. the way i look at it, the price we are charged doesn’t include pay for the diving staff. in some cases, the service they provide and their experience should provide them a real vocational living wage, at least $40-50/hr. so in some cases i try to make up for that.
i generally will throw $5-10 into the tip bucket for the support staff. if i’m just doing a day or two of fun diving, or if i’m on a proper trip but am bouncing between DMs then i usually won’t tip. if they have a system for tip sharing i’ll throw in $20 at the end of the trip. in all cases i pay for all drinks for the Pros i dive with, and if we go out to eat we cover their food.
if i take a course and have a good experience or if i’m on a liveaboard and am assigned a DM who takes care of us, then i will tip 20-40% of the total cost of the trip/course. especially if the Pro has a lot of experience.
i have tipped $400 on a $1000 liveaboard with an excellent, experienced DM who really looked after us.
i also discuss how much i’m going to tip with my group before doing so we’re all on the same page. recently took a course and the DMT assisting went above and beyond, so the other students and i decided to pay for the DMT to join us on a rather pricey fun dive.