The 37-year-old actor and Waterhouse, 25, were photographed holding hands and packing on the PDA while strolling in a local park in Mexican resort town, reported Entertainment Tonight.
The pair kept it casual with Luna sporting a blue button-down and khaki shorts, while Waterhouse donned a sheer lavender top and black, lace-trim shorts.
Luna was previously married to actress Camila Sodi. They got divorced in 2013 after five years of marriage. The former couple shares two children, 8-year-old son Jeronimo and 6-year-old daughter Fiona.