The harbour at Portovenere is the departure point for some of the best short boat trips on the Ligurian coast. The three offshore islands — Palmaria, Tino, and Tinetto — lie within a kilometre of the promontory and are best seen by water. Palmaria, the largest, has pebble beaches, a clear sea, and walking paths through scrub and maquis; the ferry crosses in five minutes and runs all day in summer. Tino is a military and monastic island, closed to the general public except on the feast of San Venerio (13 September), when a small pilgrimage crosses from Portovenere. Tinetto is a bare rock with ruins of an early medieval monastery, accessible only from the water.
Ferries also run north along the coast to all five villages of the Cinque Terre — Riomaggiore, Manarola, Corniglia (no landing; the village is high above the sea), Vernazza, and Monterosso — with multiple departures daily from June to September. This is a far more pleasant way to visit than arriving by train, and gives you a view of the villages that no road or path can match. A round-trip boat pass covering Portovenere and the Cinque Terre can be bought at the harbour ticket office.
Private boat hire is available from the harbour for those who want to explore the sea caves along the base of the promontory, swim below San Pietro, or anchor off Palmaria for the afternoon.