Playa Sonrisa is the perfect quiet getaway. If what you want is a secluded spot to chill out on a beach, relax and do nothing, and if you're happy at a clothing-optional resort then this is place.
Here are some things you should know about Playa Sonrisa before booking.
The drive from Cancun airport is (legitimately) five hours. (I don't think you can shave much time off of that.) The road is excellent the whole way, except for the last 6km, which is along a pitted dirt "beach road". But any rental car can make it safely - you don't need an SUV. And if you're coming, do rent a car, because I imagine bus/taxi in this part of the world is quite difficult.
There's almost nothing close to Playa Sonrisa: no stores, few other restaurants, no nightlife. You can drive in to Xcalak (6kms away) and they have a few restaurants and some small stores with bare necessities, but you'll want to stock up on anything you might need in Playa on the way down. The resort is "off the grid", so it's powered by solar arrays and a generator. What does that really mean? No hair driers, but plenty of power to recharge your laptop / iPod / Kindle, lights and fans whenever you want them, etc. The resort has WiFi Internet, if you're sitting in the right spot and the winds are blowing the right way, which works well most of the time.
There's a full cash bar on the honour system, with cold drinks and most liquors that you'll want. Murph and Cindy serve breakfast (included) and lunch (very reasonable, usually around 60 pesos) every day, and a very palatable three-course dinner every weeknight (100 - 200 pesos all-in). We found Cindy's soups to be outstanding, especially. On weekends when they don't serve dinner, consider the Leaky Palapa in Xcalak, which is the best restaurant we've found in Mexico (open Saturday to Tuesday, typical cost about 300 pesos per person all-in). But ask Murph to make you a reservation, as they are often fully booked.
What is there to do at Playa Sonrisa? A whole lot of nothing. Most of our fellow guests spent their time sitting on the beach or dock, soaking up sun and reading, or walking in the water. The beach there is lovely, but bring some water shoes if you want to walk in the water, as the bottom is mostly rocks, shells, or seaweed. If you're looking for pure white sand and an ocean in which you can easily swim, you might be disappointed, as the water is somewhat shallow. On the upside, there were never more than a few non-naturist people per day walking on the beach (and no vendors.)
As for the naturist aspect, we felt completely comfortable being naked on the beach at any time, and almost all other guests were similarly at ease. The resort is big enough that you never need to be close to anyone else if you want a bit more privacy - there are easily enough deck chairs and hammocks for everyone. No one seems to go nude in the bar/restaurant, although it's permitted outside of meal times.
And bring enough cash. You should budget at least 350 pesos per person per day for food and incidentals - more if you intend to drink a lot. There's no ATM in Xcalak - the closest ATMs are in Mahahual, about an hour's drive away. There's gas in Mahahual, too, and none in Xcalak.
Murph (Donn) and Cindy always went above-and-beyond to make us feel comfortable. They seem to have boundless patience, and are committed to the guest experience and naturism (which is a feat after ten years.) It was our first naturist getaway, and we can't imagine a better first time.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC