When it comes to tipping on a dive trip, you can tip anyone
you want any amount you want. It’s your business. But if you
have some regard for money, the purpose of the tip, the country
and its culture you’re visiting, as well as your fellow divers
who come from other countries, you might try to be thoughtful
rather than reckless. Of course, hardly anyone at a dive resort
or on a liveaboard will turn down a tip, but it’s not necessarily
appropriate to pass out money as you would business cards at a
convention.
After reading the hundreds of responses we received
  from our readers to our e-mail question about tipping, it’s
  clear that most divers don’t know what is “right.” Most
  Americans feel guilty if they don’t tip big, while just about
  everyone else in the world tips more selectively, tips less,
  and often never. Not because they’re cheap, but because
  they believe people should properly perform the job they
  are being paid for and that it’s not up to the customer to
  reward them a second time. They often view American tippers
  as foolish and crass.  
So if you’re an American diver and want some guidelines,
  other than what travel agents and resort and liveaboard owners
  urge us to do (15 percent, maybe 20 percent, of the total bill,
  which means hundreds of dollars that may never end up where
  you intend), you should pick those who did something for you
  tip them individually. If you jump into the tipping pool, you
  have no control over the results.  
Ben’s American Rules 
I believe tips are for the so-called working stiff - - minimumwage
  earners, people not earning a living wage, people in deadend
  jobs, and people who are neither managers, professionals
  nor owners, and who don’t get a share of the profit.  
Tips are for:  
* People who serve you, like waiters and bartenders, but not
  your butcher or the lady selling you jewelry.  
* People who clean up after you, like cabin attendants and
  maids, but not your dry cleaner or dental hygienist.  
* People who deliver things to you, like bellhops and pizza
  drivers, but not the FedEx guy or the furniture delivery man.  
* People who transport you, like a dinghy driver or a cab driver, but not an Amtrak engineer or a liveaboard captain.
* People who point you in the right direction or help you
  out, like guides who point out fish or a concierge who scores
  you World Series tickets, but not your librarian or travel agent.  
* People who touch you, like masseuses and barbers, but not
  nurses or your tailor.  
* People who save your life, like the boatman who tracked
  you down a mile from your liveaboard, but not the dive guide
  who forgot to count you.  
* And you might consider tips for the folks who work when
  you sleep, like those raking the leaves on the beach, scrubbing
  the kitchen floors, or washing the urine out of your wetsuit.  
Of course, most Aussies and Brits I know are scoffing at my
  laundry list, but remember guys, these are American rules.  
Because tips are not for owners, managers or professionals,
  it means that it’s not for chefs, trip leaders, scuba instructors
  who teach you (did you tip your underpaid high school gym
  teacher?), airplane pilots or bus drivers. Nor are they for people
  who grab your suitcase without asking, or guides who don’t
  point out fish, say rude things to you, talk behind the back of
  others, are sexist, racist and just plain stupid . . . and, of course,
  for anyone who suggests a tip, no matter how subtly. A tip is not
  an entitlement.  
If you boil all this down, the American traveling diver
  should consider tipping dive guides, tank attendants, chase boat
  drivers, and servers and cleaners. A tip pot or tipping request
  that includes the photo pro, the chef, the engineer, the tour
  director or the boat captain, to name a few, is excessive and
  ought to be ignored in favor of individual tips.  
The rule works very well on a liveaboard, where you’ve got
  plenty of time to tip people individually. It’s a little tricky, however,
  because the chef might also be the one who makes your
  bed, so he might deserve a small tip for that, but not if he fails
  to wash his hands afterward.  
At a resort, where for each day you have a different guide,
  dinghy captain and guy washing out your wetsuit, it gets tough,
  especially if you haven’t learned their names. But at many venues,
  giving a ten spot to the guide and asking him to spread it
  around is like asking a tot to share her Christmas candy – only after she gets her fill. You might feel less guilty, but you may
just be empowering a bag man.
When in Rome...or Raja Ampat  
No matter where you go, most everyone you tip will be a
  local (though some guides might be American or Aussie). If
  you follow my approach, you should then fashion a tip based
  on local standards, which may not be easy to figure out, but
  give it a shot.  
For example, with a quick Google search I learned the
  average wage in Bangkok is less than US$30 a day, but that’s
  weighted by high-income earners. When you go lower down
  the income levels, it’s more like $10-$15 for office workers
  and even less for laborers. Minimum wage is around $6 per
  day.  
In Indonesia, where the minimum wage is $3 a day, local
  crew excluding dive guides generally make $50 to $150 a
  month. Local dive guides range between $100 to $700 a month.
  Expat dive guides/cruise directors, usually around $800 to
  $1,500 a month, some more. In Papua New Guinea, laborers
  may make $100 to $200 a month and dive guides more.  
So in countries like this, I think a tip of $5 a day would be
  fitting, even generous. If the person was serving 12 divers on
  a liveaboard, he’d be getting twice his wage in tips (he can be
  paid less and still be paid fairly if he is fed). If he were my private
  guide, I’d give him $10, maybe $15. If someone in a hotel
  carries your bag, a five-spot is not the appropriate tip; two-bits is
  closer to it.	
If there are five people on the liveaboard who meet my tipping
  criteria, then I should be shelling out $250 for a ten-day
  trip. Divers who think 15 percent of a $3000 trip would be shelling
out $450. 
The Caribbean, of course has a higher standard of living
  and pay scale. In the Cayman Islands, depending on what
  island and what resort, monthly wages range from as low as
  US$1,000 to nearly $2,000. Tipping $10 to $15 per day total for
  those involved – you pick ‘em – seems fair. If you’re tipping
  everyone all at once on a $1,500 bill for the week, then $150
  to $200 would make sense – if you’re an American. If you’re
  Canadian or a Brit? Well, at least buy your dive guide a pint
  or two.  
Do You Know Where Your Money Is Going?  
Of course, the operators, who rely on tips to ensure their
  staff is paid enough to stay on the job, won’t be happy with
  what they will see as a parsimonious approach from Americans
  with deep pockets – after all, we Americans are subsidizing
  all those other divers who don’t tip. But let us remind them of
  cruise ships. These days, tipping is becoming standardized. It’s
  $10 a day per person for everyone but the bartender, who is
  tipped separately. And you, with the deep pockets, should keep
  in mind that if you’re traveling with Europeans, Aussies and
  Kiwis, you might be the only one tipping. And they’ll consider
you daft. 
Regardless of what leaders tell you about the fairness of
  their community pots, you have no control over how it’s disbursed
  so you can’t be sure of the distribution formula. While
  the money often gets to the hardworking soul who just cleans
  cabins or tends to the engine, it may not. So carry a dozen
  plain envelopes, lots of small bills, and pass them out to the
  people whom you want the tips to reach.  
And tip for the service you received, not so you’ll be remembered
  when you return. That may make sense if you go to the
  same bar or restaurant every Friday night, but if you’re going
  back to Captain Don’s or Beqa Lagoon Resort once a year,
  chances are most everyone you dealt with has moved on, and if
  not, you’d be remembered only if you dropped a hundred-dollar
  bill everywhere you went. Sure, you “felt like family,” but a
  hundred people a week leave feeling like family.	
Finally, of course, you can tip anyone any amount you care
  to. It’s your money and you can give it away. However, there’s
  something gauche about an American tossing money around,
  and while you might put a moment of joy in the hands of the
  recipient, a little prudence will benefit the greater good. And if
  you still feel like a cheapskate, give it to a school or library. At
  the airport, drop it into one of those buckets for a local charity.
  Instead of tipping the photo pro or the tour director who makes
  living wages, you can feed five families for a week.  
I asked several people to read and comment on this before it
  went to print. Here are two views I want to share. 
John Bantin, Technical Editor of Diver in the UK, says this:
  “Yours is an interesting yet uniquely American perspective on
  tipping. I believe it is best to do what is considered normal
  in any situation. In America, people who serve seem to live
  on the tips they get but in the EU, people must be paid a
  proper wage. In some countries like Papua New Guinea, not
  only is tipping not normal but it is actively discouraged. In
  Thailand, everyone hustles for more. When you tip a liveaboard
  boat crew, often it is the people you never see who
  deserve the most, such as the engineer who stayed up all
  night to mend the compressor or fix the sanitation flush, so individual tipping is often unfair. And giving 10 percent of
the cost of your holiday is a ludicrous idea that makes other
people think Americans have got more money than sense.”
Ken Knezick, American owner of Island Dreams Travel
  in Austin, had this comment: “Personally, if I ‘overtip’ and it
  helps to change someone’s life, then I am happy to be able to
  do so. I don’t think we are required to perpetuate disparities of income and lifestyle. I have been graced with much good
fortune, be it due to luck of birthplace, education, opportunity,
and a body and brain that work. Sharing that wealth is
part of what makes me who I am. On the other hand, I have
had a resort manager tell me, ‘Don’t spoil the wogs.’ What a
pitiful attitude.”
- - Ben Davison