The Riviera Maya is in Quintana Roo in the Yucatan Peninsula
The Riviera Maya is in Quintana Roo, a Mexican State in the Yucatan Peninsula. In the map of the northern tip of the Yucatan Peninsula, you can see that Cancun is in the state of Quintana Roo.
The Riviera Maya, a tourist designation, extends along the extreme eastern coast of Quintana Roo along the Caribbean Sea (also on the right).