Ponza is long, thin, and crescent-shaped, with wide scalloped bays on the east coast and a more jagged profile on the west coast. Near the southern end of the island, facing east, is Ponza town, often referred to simply as Porto. This is the only part of the island with comprehensive services, and in summer, Porto heaves with activity. The main square is Piazza Pisacane, from which the main drag of Ponza, Corso Pisacane, runs west, with one side open to the marina. The street and piazza are lined with shops, cafes, and services like banks, pharmacies, and the post office.
In the evening, Corso Pisacane is the prime venue for the Ponzese passeggiata ritual. On Ponza, however, it's not so much about strolling up and down the street as doing a "static" version of the passeggiata -- by leaning or sitting on top of the long ochre wall that follows the outer curve of Corso Pisacane and the old fishing marina. Throughout the day, locals and vacationers alike take a break along the wall, gelato or granita in hand, either facing the water to watch the boat activity or inland to watch the parade of people go by on Corso Pisacane. (This being Italy, most people choose to face inland.) Back down at the water, busy Via Dante skirts the port, where there are dozens of boat rental agencies and waterside restaurants.
The semi-circular marina of Porto is mirrored on the west coast by Ponza's most famous beach, Chiaia di Luna. Only 500m (1,640 ft.) of land separates them, so it's only a 10-minute walk from hectic port to spectacular beach, by way of a 2,000-year-old Roman tunnel. (Chiaia di Luna is closed as of press time but may be reopening in the near future.) When it is open, this is one of a few good swimming areas on Ponza where you don't need a boat, and, in fact, it's better to come by land.
Not much else is within practical walking distance from Porto, so you'll need to take a bus or hop on a boat to see the rest of the island. Buses run from Via Dante to points north; if you want to take the bus simply as a way of sightseeing by land, allow about 45 minutes round-trip (without getting off). A few of the stops along the way put you within a short walk of swimming coves, including Cala Feola and the Piscine Naturali, although for others it's a significant hike, in which case you're much better just taking a boat around the island. When trying to reach a beach by bus, always ask the driver where to get off. The end of the bus route is the tiny village of Le Forna, where there are a few sleepy shops to serve the vacation rental community here.