The couple was spotted kissing and hugging and enjoying a romantic boat ride on Sunday, July 1 on Muyil Lagoon, near the Mayan ruins.
Eiza opted for a gunmetal bikini, while Josh wore red-trimmed white swimming trunks and a white T-shirt on the trip.
It was the month June when the duo first stepped out together for a dinner date in Los Angeles and since that month, they were photographed again a couple of times, including at another restaurant, where they packed on some PDA.
the Transformers actor and The You Already Know singer, 42, began dating in September 2004 and eventually got married in Malibu in January 2009.
Unfortunately, after enjoying a romantic marital relationship for eight long years, they announced their split in September 2017. The duo shares a son Axl Jack Duhamel, 4, together.
Eiza, meanwhile, previously had affairs with actor Liam Hemsworth and businessman Pepe Díaz.
Both Josh and Eiza has yet to comment on their affair. For more updates, stay tuned to Frostsnow.