The rock-cut tombs of ancient Kaunos, carved into vertical limestone cliffs above the Dalyan River in the fourth century BCE, were designed to resemble Ionic temple facades — pilasters, pediments, false doors — so that Persian-influenced Carian nobility could ascend symbolically to the afterlife. The largest, the Temple Tomb, stands fifteen metres tall and faces southwest, catching the evening light that turns the sandstone orange. When Caunos flourished as a port between 400 BCE and 200 CE, the river mouth lay open to the Mediterranean; silt carried downstream from the Köyceğiz basin gradually closed the harbor, and malaria finished what geology began. By the Byzantine period the city was abandoned, leaving only the tombs to mark its former prominence. Today the Dalyan River remains navigable for flat-bottomed boats that ferry visitors between Köyceğiz Lake and the Mediterranean coast. The twelve-kilometre channel threads through protected wetlands designated a Special Environmental Protection Area in 1988, the year Turkey recognized that İztuzu Beach — the four-kilometre sandbar separating river from sea — served as one of the Mediterranean's last major nesting sites for Caretta caretta loggerhead turtles. Between May and September, female turtles return to the beach where they hatched, digging nests above the high-tide line and depositing clutches of eighty to 120 eggs. Hatchlings emerge after fifty days, orienting toward moonlight reflected on water. Development pressure in the 1980s threatened to pave the beach for resort hotels; conservation protests led to zoning restrictions and seasonal night-time access limits that remain in force. Most Marmaris to Dalyan boat trip itineraries combine the tombs, thermal mud baths, and turtle beach into a single circuit. Boats depart Dalyan's central quay and motor upstream toward Sultaniye hot springs, where visitors coat themselves in mineral-rich clay that dries to a pale grey crust before rinsing in 39-degree Celsius sulfur pools. The return leg stops beneath the Kaunos tombs for photographs, then continues downstream to İztuzu, where shallow lagoons on the river side offer calmer swimming than the open Mediterranean beach. The delta supports reed beds, egrets, and Dalmatian pelicans; silt patterns shift annually, and sandbars appear and vanish with winter floods. Archaeological excavations at Kaunos, conducted intermittently since 1966, uncovered a Roman bath complex, a Byzantine basilica, and inscriptions in Carian script — a pre-Greek language still only partially deciphered. The site's amphitheater, seating capacity 5,000, is accessible by land from Dalyan town but not included in standard boat excursions. Ticket revenue from the tombs funds ongoing conservation at İztuzu, where nesting success rates have improved since protective measures began, though plastic pollution and erosion from boat wakes remain persistent threats.