Small wooden fishing boats rock gently in the luminous turquoise shallows off Isla Mujeres — one with a bright red gunwale, another a classic sloop with bare mast — in this idyllic chrome-era view of the tiny Caribbean island off the Yucatán coast, long before Cancún's resort towers changed the horizon forever. The senders, signing as "Shel & Bob," wrote to their friend Hogarn in Fairport, New York, painting a picture of barefoot paradise: a boat trip to Isla Mujeres, lazing on the sand, skin diving, buying fresh fish directly from local fishermen, and scoring fresh lobster for five people for just $9.60. "Ground blue H₂O," they marvel — the postcard's image barely doing justice to what they describe as "clear, bright" water. Mailed from Quintana Roo (then a sparsely populated federal territory, not yet a state), this card captures the Caribbean coast of Mexico as it existed in the last years before mass tourism arrived. The 80-centavo Correo Aéreo stamp pays the airmail rate to the U.S.