We originally visited Tulum ruins on a day trip from Cancun. After the rest of our family left Mexico, we decided to come spend a few more days in the Tulum area. We stayed at Copal which is just a mile or so south of the town of Tulum along the road to Sian Ka'an. Like the majority of hotels along this stretch of coast, there is minimal electricity and no fresh running water in the rooms (Copal has salt water showers). Copal consists of several rows of thatched huts. There is electricity at the front desk and in the restaurant but not the rooms. The lack of fresh water is not much of a hardship as there is a fresh water jug in each room. To be honest, it may well not be worth staying here if you can't get one of the huts along the ridge overlooking the ocean. The constant sea breeze makes it very pleasant but the inland trails are substantially hotter and there are more insects.
Plus, if you stay beachfront you can have a front porch like this. There isn't a much better way to spend the evening than sitting here with a tequila-laced beverage watching a distant thunderstorm out at sea. Copal has a couple contiguous sister resorts as well, one is slightly more upscale, the other aimed at families. Sleeping at night in the heat was a little difficult. We were faced with the choice of keeping the door and the mosquito netting closed which made it quite hot, or leaving both open which allowed the breeze in and made it very pleasant. Of course then you had the risk of assorted critters visiting. Since it was off-season, the prices were unbeatable so there was no doubt in our case that it was well worth staying here.
Copal has a beach and oceanfront bar on the north side of the property. From there you can walk almost all the way to the Mayan ruins of Tulum. The ruins are the primary draw for most tourists to the area. There's practically a small mall in front of the ruins including street performers (mostly of non-Mayan traditions). The town of Tulum is only another mile down the road (MX 307) and is far more reasonably priced, so if you have a car, it's worth eating in Tulum town which is a few blocks long and a few blocks wide.
We've visited a lot of other Mayan ruins and while Tulum is nicely restored and does have a few stelae and a couple buildings where the original engravings and colors can be seen it's not really about the history here. Tulum was a relatively small backwater harbor town during the Mayan ages. The setting is quite spectacular however, especially in contrast to the larger inland Mayan cities.
There are guided tours of Tulum, but they're not necessary with any guidebook really (and there are plenty available). The restored area is compact and the entire site can be seen in under an hour.
There is a beach accessible directly from the ruins as well. It can be pretty narrow at high tide but like the other beaches in the Tulum area it has fantastic white sand and the water is almost too warm to be refreshing.
If you're looking for colder water, you might want to try a cenote. This is Gran Cenote which is about 3 miles (5 km) north of the main Tulum junction on the road to Coba. There's an entrance fee and a short walk to a giant circular hole in the limestone. Gran Cenote is part of an enormous underground aquifer system that stretches for hundreds of miles across the southeast Yucatan.
A platform has been built on an island in the center of the depression, giving access on all side to the cenote itself. On one side the water passes through this open cave to a second jungle clearing (and further caves beyond).
The water is remarkably clear and there are many freshwater fish species around. The cenote water stays at around 72 degrees F (22C) year round. Most common insect repellents and sun tan lotions are not allowed here to keep the water unpolluted.
There are four connections out of Gran Cenote to the rest of the aquifer system but you won't be following them without some serious cave diving certifications and a good guide. The pool is quite shallow on the far side (above pictures) but this cavern is about 10m (33ft) deep.
South of Tulum, a dirt road winds along the spit of land between the ocean and a series of large brackish lagoons. Eventually you enter the Sian Ka'an biosphere reserve. Cesiak, which operates as part-hotel part-national park office is located here. In this picture, taken on their rooftop observatory you can see the ocean on the right and the lagoon on the left. Further down the road are a couple of very small, sleepy fishing villages and eventually the end of this peninsula.
We rented a kayak at Cesiak. They do offer guided tours but we intended to just take a kayak out on our own. If you are planning to do this, make sure you're well equipped (water, compass, sun protection) and are competent in a sea kayak. Basically, one member of the staff took us up to the roof and pointed sites of potential interest out from here. Manatees over by that island, flamingos over that way, etc… Then we went down to that little thatched hut visible in the foreground and off we went with the final warning: "oh yes, we have a healthy crocodile population, don't go swimming". Hooray.
We did not go swimming. Our instructions were to pass through a gap in the mangrove islands and then follow the sounds of the birds. This seemed a bit sketchy but worked out great. Frigate birds make most of the noise as there are hundreds of them nesting here. Cormorants, flamingos, ibises, herons, pelicans and probably others that we've forgotten also nest on these mangrove islands.
If you really just want to see a flamingo in the wild, there are better sites along the north coast of the Yucatan but we spent some time pursuing a lone skittish flamingo around and around a series of hammocks. Later we did the same thing with a roseate spoonbill. Mangrove islands are notoriously easy to get lost in and many of the narrow waterways are choked with vegetation so it's worth mentioning again that if you go out on your own here you should be competent with a compass. When the wind isn't whipping up waves on the main lagoon the water is clear enough in the shallows to see fish, crabs, and snakes (and presumably crocodiles).