Want to explore Mayan ruins like this? This is just 1 of 23 ruins found on the Sian Ka'an Biosphere Reserve in Tulum, Mexico. Exploring ruins not your thing? The reserve offers many other tours, from snorkeling all the way to a leisurely boat ride down an exotic river. Sian Ka'an has 1.3 million miles to explore, so they'll never be a dull moment! And since the reserve is a UNESCO World Heritage Site, you can rest assured that you are promoting ecotourism!