A few things I didn't see mentioned earlier or missed:
Depends a lot on where you go and what you are planning to do.
at least if you use a credit card, the merchant adds a fee (usually about 3%) to cover his CC costs. Thus paying with cash can save money, and ATMs are readily available -- just make SURE you use on in a bank. Those in stores, etc are notorious for being hacked.
Also in Mexico
at least it is normal for marinas
to charge dockage (and often fuel) in dollars, then convert it to pesos at a rate advantageous to them. Then if you use a credit card, the fee is added, it gets charged in Pesos, then the CC company converts it to US dollars and charges you another fee. So the bottom line is that it is often cheapest to pay in US cash.
Many local services (mechanics, boat minders, boat yard, etc) will also quote in dollars and you will often find the work is less expensive if you pay in dollars than in pesos. Common "non-boater" services and goods are paid in Pesos of course.
Thus, at least here in Mexico, having enough US cash on hand can be advantageous.
Note that US dollars are available at a very few ATMs, but it is comparatively expensive.
Note that when using ATMs, if will be to your advantage to use a debit card tied to a checking account rather than a credit card. Moreover, if you shop around, there are several cards that charge no foreign transaction fees
, and a few that rebate the ATM fees
. Over time, these charges add up.
Finally, note that the $10,000 "limit" is per person, not that we ever need near that amount of cash in a normal 6 month season. We find that in Mexico the most we spend in US cash might be $1000/month if we are staying in a marina. Much less of course when anchored out.
Remember -- much of what I have said pertains to Mexico, but some is universal. So pay attention to local customs
. And don't forget to keep some cash (preferably both US and local) stashed away for emergencies such as wallet lost
or stolen etc.