Excursion boats tie up in Kaleiçi's Roman Harbour. One-, two- and six-hour trips are offered (€10/15/30 at the top end; your accommodation can likely get you a better deal). The latter includes lunch and stops such as Kemer, the Gulf of Antalya islands and some beaches for a swim. Additionally, ferries (₺10) run from the harbour to Kemer marina at 9am, noon and 5pm, returning at 10.30am, 1.30pm and 6.30pm (less frequently in winter).
For ferry times and information, visit www.antalyaulasim.com.tr.