Go cave diving in the cenotes
The freshwater cenotes aren't just about swimming – you can dive in them, too. Under the water you've got limestone caves packed with stalactites and stalagmites. The visibility down here is so good – it reaches around 45 metres – that divers compare the experience to space travel. If you'd rather see more in the way of marine life, you can dive the reef to see turtles, squid and barracuda.