The preferred method of travel from Athens to Spetses is by sea from the port of Piraeus. In high season several passenger-only hydrofoils and catamarans of Hellenic Seaways depart the port of Piraeus daily, calling at the the islands of Poros, Hydra and Spetses, as well as the mainland ports of Ermioni and Porto Heli on the Peloponnese. Depending on the ports of call, trip duration from Piraeus to Spetses is between 1 hour 45 minutes and 3 hours 15 minutes. Passenger tickets cost €35 one way.
Only the regular ferry carries motorcycles and bikes to Spetses. Private cars are not officially allowed on the island.
Winter sees a major reduction in service, with only four hydrofoils daily. These are subject to cancellations when the weather turns nasty.
Due to its proximity to the mainland, many choose to travel to Spetses overland, parking their cars (€5 per day) at Kosta on the Peloponnese and then crossing over either on one of the four daily landing-craft ferries (15 minutes, €0,85) or by sea-taxi (3 minutes, €15). Public Inter-City (KTEL) buses  connect with the ferry at Kosta, to/from Athens and Nafplion daily year-round.
With private cars officially banned from the island, local transportation is very expensive (although most attractions are within reasonable walking distance). In high season there are two buses connecting the town with the beaches of Aghioi Anargyroi and Aghia Paraskevi on one side and Ligoneri on the other side. Other land transportation includes four taxis and several horse-drawn buggies (high season only). Plenty of bikes and motorcycles are available for hire.
In summer tourist boats provide day trips to the beaches of Aghioi Anargyroi, Aghia Paraskevi and Zogeria. Water taxis are also available year-round, connecting Spetses Town with any beach on the island or the coast of the Peloponnese, just across the narrow straits, but these can be very expensive.
Low-season options are restricted to water-taxis and the four land-based taxis, with the horse-drawn buggies withdrawn from circulation and the buses assigned to transporting students to and from schools.
Several of Spetses innumerable cafes offer internet service for a fee, but exactly which ones seems to keep changing. Look for signs saying Internet, or ask at your hotel if they can direct you to one.
Spetses has two museums. The Hadjiyannis Mexis Museum is located to the southwest of the town--a five-minute walk from the harbour. Open daily except Monday 08:00-15:00 (admission €3) it is housed in the late-18th century mansion of Hadjiyannis Mexis, one of the local leaders during the 1821 War of Independence, and includes objects from throughout the 4,000-year history of the island.
The privately-owned Bouboulina Museum is open daily in high season, with guided tour provided in Greek and English several times a day (admission €5). The museum is housed in the 17th century mansion of the 1821 War of Independence heroine, Laskarina Bouboulina and mainly exhibits artefacts from that period.
Other interesting attractions include the Mansion of Sotirios Anargyros, an early 20th Century neoclassical building, home of the local benefactor Sotirios Anargyros (1849-1929), just behind the waterfront cafeterias in Spetses Town.
To the north of town are the Poseidonion Hotel and the Daskalakis Electricity Factory. The Poseidonion was constructed in the early 20th Century and attracted the rich and famous of Athens in its heyday, but has fallen into disrepair as of late. Renovations began in 2006 to convert it back into a luxury hotel. The Daskalakis factory, which used to provide the island with electricity and ice, has been converted into a luxury hotel.
The celebrations of the Panaghia Armata are the highlight of the summer season on Spetses, attracting as many as 40,000 visitors, and culminating in the re-enectment of an 1822 naval battle between the Greek forces and the Turkish Armada. The show includes an attack on the Turkish flagship with a Greek fire-boat, which sets off a fascinating show of fireworks in the harbour of Spetses Town. The week-long celebrations culminate on the second weekend of September each year, and also include concerts and other cultural events. A special mass is held in the church of Panaghia Armata in the Old Harbour, as well as at Aghios Nikolaos, the metropolis of the island.
Easter is also a very popular time for visiting the island. Holy Week traditions are lovingly passed on from generation to generation, with the highlights being the Good Friday mass, where funeral processions from all parishes converge on Spetses Town for a final open-air mass, and the Saturday midnight celebrations of the Resurrection with fireworks (before everyone returns home for the traditional feast that marks end of a 40-day fast).
Accommodation during the Easter and Armata weekends can be impossible to find, unless booked well in advance.
A walk to the Old Harbor is considered a must for visitors to the island. The coastal road is closed to vehicles in the evenings during summer season, making it a pleasant outing all the way from Spetses Town, past some of the most spectacular mansions, and on to the marina with all the luxury yachts and cruisers of the wealthier holidaying Athenians, all the way to the little churche of the Panaghia Armata and the Lighhouse--one of the first to be built in Greece, in 1837, and still in use. At a leisurely pace the walk from the new Dapia harbor at the town center to the Old Harbor shouldn't take more half an hour each way. Cafes, bars and restaurants abound in the Old Harbor.
The island's most popular beaches are Aghioi Anargyroi and Aghia Paraskevi, on the west side of the island. A bus and tourist boats run daily from Spetses Town during the summer season. An acceptable, if somewhat touristy, self-service restaurant operates in-season at Aghioi Anargyroi. The Bekiris Cave at Aghioi Anargyroi, complete with its own sandy beach, is a must-see. Access is overland from the northern edge of the Aghioi Anargyroi beach, or else you can swim inside through a very low opening. The cave served as a hideout for women and children during Turkish attacks on the island.
The very picturesque Zogeria Beach, on the north edge of the island, is also served by tourist boats from the island and boasts a restaurant, serving its specialty of chicken in tomato sauce with spaghetti or chips.
Other beaches on the island, such as Xylokeriza, Ligoneri and Vrellos are only accessible by private transport (motorbikes or bicycles) or with very expensive sea taxis.
The town beach at Aghios Mamas is rather dirty and crowded, but could suffice in a pinch. It's better to continue south to the tiny beach beneath Aghios Nikolaos, or even further to Aghia Marina.
There are also series of beaches beginning past the Spetses Hotel about a twenty minute walk along the main island road west of the main Dapia harbor, of which the most pleasant is Kaiki Beach (so called from the beached hulk marking it) across from Anargyrios College (hence also called College Beach.) This beach is typically developed: a bar, a (rather basic) rest room, a little changing shack, and sun beds under Polynesian style umbrellas for rent. Right next to it is a public beach with fewer facilities, but the water isn't there isn't as good for swimming and that part of the beach tends to be littered. The water at all the beaches on this northern stretch of the island can be too rough for pleasant swimming when the wind is up.
Other interesting sights to visit:
The local specialty of Spetses (as also of many other Greek islands) are Amygdalota, little almond cakes, sprinkled with icing sugar. The most popular are available at the well-established pastry shops of Klimis and Politis.
Restaurants abound in Spetses, especially in the high season, ranging from local fast-food outlets to posh, haute-cuisine affairs. Several remain open even in winter, when food is often served around the fireplace.
Many of the popular bars of Spetses are located around the Old Harbour, which is the place to see and be seen for most Athenians holidaying in Spetses. There are also several popular cafes and ouzeris clustered around the main Dapia harbor, and several more scattered along the coastal road leading northwest from town.
Almost all accommodation is in Spetses Town, generally in one of three areas. There are several large hotels and also rent-room places right in or near the main Dapia harbor, which is convenient but can be noisy. There are some studios a twenty minute or so walk away to the east, around the Old Harbor, more atmospheric but a little out of the way. About an equal distance from Dapia the other direction are a number of hotels and studios, most notable of which is the Hotel Spetses: this area is not particularly atmospheric away from the shore, but it is relatively quiet, and is located conveniently to Kaiki Beach and to the Patralis restaurant and to a number of other pleasant restaurants and cafes.
Plenty of hotels cater to visitors on the island, but rooms tend to be tiny, prices high and service mediocre. Advance reservations are highly recommended during summer months weekends, as well as during Holy Week at Easter. Rooms to let are also available, with owners sometimes meeting arriving boats.