We are headed to Playa del Carmen next week. I don’t know your exact destination, OP, but I’m guessing it’s a well traveled tourist area if not an all-inclusive resort. As the others have said, this is not like the areas of Mexico you hear about on the news, and ISIS is no more there than it is in any US tourist destination. That is, .000000001% chance that a radical wing nut will ruin your holiday.
Especially in the popular areas of Playa del Carmen, there are plenty of other tourists and it’s very laid back and comfortable. Stay where the people are, whether that’s at your hotel or in whatever town or tourist attractions you visit, use common sense, don’t flaunt your valuables or cash, and you’ll be ok.
p.s. We had the same conversation with my in-laws the first few times we went. MIL couldn’t figure out why anyone would want to go hang out in a third world country full of drug runners and dirty people who didn’t even speak English. She was scare half to death the whole time we were gone, but she acted the same way when we ate sushi or mushrooms, too. Very different attitude toward new things. I guess it’s all in what you choose to hear and believe.
