Sian Ka’an (Where the Sky is Born) is home to a small population of spider and howler monkeys, American crocodiles, Central American tapirs, four turtle species, giant land crabs, more than 330 bird species (including roseate spoonbills and some flamingos), manatees and some 400 fish species, plus a wide array of plant life.
There’s an entrance gate to the reserve about 10km south of Tulum. At the gate, there’s a short nature trail taking you to a rather nondescript cenote (Ben Ha). The trail’s short, so go ahead and take a second to have a look.
About 8km south of the reserve entrance is a modest visitor area, a pull-off where you’ll find a watchtower that provides tremendous bird’s-eye views of the lagoon.
The road can be a real muffler-buster between gradings, especially when holes are filled with water from recent rains, making it difficult to gauge their depth. The southern half, south of the bridge beyond Boca Paila, is the worst stretch – some spots require experienced off-road handling or you’ll sink into the mud. It is doable even in a non-4WD vehicle, but bring along a shovel and boards just in case – you can always stuff palm fronds under the wheels to gain traction – and plan on returning that rental with a lot more play in the steering wheel.
There are no hiking trails through the heart of the reserve; it’s best explored with a professional guide. If you'd like to see more of Sian Ka'an, Maya-run Community Tours Sian Ka'an runs various expeditions into the sprawling biosphere reserve.
For remote coastal camping, this is where intrepid adventuring really takes off. Bring a tent, a couple of hammocks, lots of water, mosquito nets and food supplies. Around 30km from the entrance gate is an excellent camping spot with the lagoon on one side and glorious blue ocean on the other.