The Mona Passage between Puerto Rico and the Dominican Republic is one of the humpback whale's main migration routes. From roughly December to March, pods of humpbacks pass through Rincón's waters, and spotting them is reliable enough that several local operators offer dedicated whale watching excursions by boat.
Humpbacks can sometimes be seen from shore — the Punta Higüero lighthouse promontory is the best land-based vantage point. Breaching and tail-slapping are common in the Mona Passage. For closer encounters, the two-to-three-hour boat trips from Rincón's small marina put you among the whales in open water. Tours run daily when conditions are good; book ahead in the peak January-to-February season.