I was recently vacationing in Playa Del Carmen and finished the only book I brought. I'd hoped…read morethere would be a "book swap" at our condo building, but there wasn't. Luckily we found Gandhi located just a 10 minute walk from our place. It's a small but mighty little bookstore, packed with books in multiple languages (including a substantial English-language section). They had several recognizable best sellers as well as true classics. And they even had a copy of a book that's been on my Goodreads bookshelf for years!
Their prices are a pretty much full retail, so don't expect the "big box" discount you might be used to. But if you're in PDC and in need of a book to read, you've come to the right place! (They also had a lovely little stationary section with journals, gifts, games, and art supplies too.)