Between you and me, I run a business (not a scuba business, but a business nonetheless) back in my area in the USA.
Credit card fraud is a felony, its a serious crime, and I highly doubt that any guy who is intelligent enough to own a successful scuba business in a nice resort area, is going to be retarded enough to steal your card (no offense but im just saying haha). If he is successful and financially well-off enough to own a scuba company, then he is LIVING THE DREAM, and no offense but dont flatter yourself, he aint wanting to steal your card bro lol.
Like for lack of a better way of putting it... Nobody is gonna throw their entire life away just to get access to your credit card. It just isnt that damn important haha. That's something some random ghetto person would do, and not a licensed, certified, and successful business owner.
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Anyway as for my business...
RIGHT NOW, we use a secure payment online form that we email to our customers, and they fill it out securely, without me/anyone on our company staff hearing it or seeing the card info. I am sure some customers appreciate that (plus it saves us valuable admin time).
HOWEVER BEFORE, we had a different merchant (who actually charged us more money, annoyingly enough) and we had to take the payments over the phone, to input it into our system. We had to do this bcuz we didnt have the OPTION to email them any payment forms. Our old one was called Vantix. Our new one, I forget what its called but it works much better and doesnt need me to hear the card info.
I NEVER EVER HAVE STOLEN SOMEONES CARD INFO. A couple times (very rare occasions) I had potential customers remark that they "werent comfortable" giving their card info over the phone, but in those cases, those people were over cautious and they lost a great company to do business with.
99.9% of customers paid me over the phone with no incident, and of course, we promptly sent them the receipt form. Apparently, Vantix had many thousands of businesses (large and small), so apparently the "card over the phone" thing is very common for small businesses.
We have had like 400+ customers during that 2 year time period where we used that form, who didnt have any problems with it. None of them had an issue with it, except the 2 people (who to me, seemed paranoid).
If anyone fraudulently charges your card, you have a legal right to do a chargeback- and you get your money back, no questions asked.
If you are particularly worried, you can ask to receive a written invoice first, stating exactly how much they will charge your card, and no more. This way you have proof of the amount you are supposed to be paying.
In my case, the only times people tried chargebacks on me (annoyingly enough, again) is when the charge WAS legitimate, and they just wanted to "cancel" last minute (cant do that once they had signed a legal contract) or they were just cheap and didnt want to pay for a completed project that our company did for them. I had to take both of those people to small claims court, and I won of course.
My personal recommendation is: CHECK THEIR ONLINE REVIEWS.
If they have a ton of good reviews, and nobody said anything about "oh they stole my credit card info", then I think it is pretty damn obvious they wont steal your credit card info, no offense brohan lol.
However if they dont have any reviews, or the reviews are all recent and seem fake, then perhaps use a different scuba place. However even with few reviews, its still an unlikely thing that they would steal your card info.