The Intracoastal Waterway threads through Jupiter as a brackish ribbon where the Atlantic tide meets freshwater springs, forming one of South Florida's densest concentrations of bottlenose dolphins and West Indian manatees. Jupiter river tours navigate these protected channels year-round, tracing a route that parallels the Jupiter Inlet and the red-striped lighthouse that has guided vessels since 1860. The waterway was dredged and connected in stages between 1881 and 1912, transforming a series of tidal creeks and river mouths into a continuous passage that now stretches from Boston to the Florida Keys. By the 1920s, Jupiter had become a staging point for rum-runners and sportfishing charters; today the same waters host eco-tourism operators and marine research teams monitoring loggerhead nesting beaches. The landscape alternates between open bays and narrow mangrove tunnels. Red mangroves anchor the shoreline with prop roots that harbor juvenile snook and sheepshead crabs; black mangroves occupy the higher ground behind them, their pneumatophores rising like snorkels through the mud. Ospreys nest atop channel markers, and roseate spoonbills wade the shallows at low tide. Jupiter's stretch of the Intracoastal lies within the Loxahatchee River watershed, a National Wild and Scenic River and the southernmost river in the continental United States classified as such. Water temperatures hold between 72 and 84 degrees Fahrenheit, supporting tropical and temperate species in overlapping ranges. Dolphins hunt mullet schools in coordinated arcs; manatees graze on seagrass beds that line the deeper channels. The inlet itself is a dynamic cut subject to shifting sandbars and swift currents, navigable only by captains familiar with the tidal schedule. Waterfront estates line the barrier island to the east, their private docks extending into the channel. DuBois Park occupies a shell mound built by the Jeaga people over two millennia; archaeological surveys have recovered ceramics and tools dating to 500 BCE. The park's lagoon offers calm water for kayak launches, while the inlet beach faces the open Atlantic. Jupiter Inlet Lighthouse and Museum stands 108 feet tall, its Fresnel lens visible 18 miles offshore. The tower is built from bricks fired in Philadelphia and shipped by schooner in 1859; it remains an active aid to navigation under Coast Guard authority. Tour operators departing from the Jupiter area offer narrated cruises that interpret the ecology and maritime history of the waterway, with routes ranging from one-hour loops to half-day excursions upriver to the cypress swamps of Jonathan Dickinson State Park. Seasonal variations affect wildlife activity: manatees congregate near warm-water discharges in winter; tarpon migrate through the inlet in spring; sea turtle hatchlings emerge on adjacent beaches from July through October. The waterway remains a working channel, hosting commercial fishing boats, sailboats bound for the Bahamas, and recreational vessels moving between marinas.