Sifnos  is a small island of about 35 sq. miles with a population of about 2,200, located within the Western Cyclades. Inhabited since very early times, Sifnos's main claim to fame in the ancient world was for its gold and silver mines, some remains of which still exist, as a result of which the island became known by the 6th cent. BCE as one of the most prosperous places in Greece. This wealth was reflected in the Treasury of the Siphnians at Delphi, which was reputed to be one of the most opulent buildings at that shrine; its foundations may still be seen there today. The Greek historian Pausanias records that the island's gold mines were destroyed in an earthquake caused by Apollo after the islanders, out of greed, sent as tribute to Delphi a gold-gilded egg instead of the solid gold one which they had traditionally sent before. By Hellenistic times, the island's golden age had passed, and its subsequent history is subsumed in the general history of the Cyclades.
In its geography and climate Sifnos falls naturally into two halves, the western part, where most ferries land, being bare and rugged, while the eastern part, which most visitors find more amenable, has somewhat more gentle terrain and is greener. Unfortunately mass tourism has destroyed most of its traditional atmosphere.
Daily or almost daily fast boats and steamship ferries connect Sifnos with Piraeus during high season (the ride takes about five hours by steamship, about half that by fast catamaran). On summer weekends and holidays some of the fast boats can sell out, so if you're going at these times you may want to buy a ticket in advance. In summer there are buses every hour or two from Kamares to most other points on the island. There are usually also taxis waiting when ferries arrive, but sometimes these can fill up. Some hotels offer transfers from the port at rates that can be anything from free to more than a taxi; if interested, ask your hotel when you reserve.
All ferry and high speed companies : schedules, connections, availability and prices, between Sifnos, other Greek islands & Piraeus port (Athens) is here 
Sifnos does not have an airport of its own. If you want to travel by plane, go to nearby Milos and take the ferry to Sifnos from there.
Sifnos is one of the easier Greek islands to get around with or without a car. Roads are generally good. The conveniently frequent and reliable bus system goes most places the visitor would want, and taxis are easily available with affordable fixed rates between towns. Sifnos is small enough so that walking will often get you where you want to go, provided you can handle the hills, though in summer you should take water and avoid the heat of the day, since as in most Cycladic islands there is little shade.
Sifnos offers little for the avid shopper; even the usual tourist souvenir shops are few. There is however quite a good though pricey jewelry shop in Kastro on the road overlooking the sea. In Apollonia there is a shop on the path leading to Petali that sells interesting old prints, and the Gerontopoulos sweet shop (22840 32207) on the ground floor of the Hotel Anthousa sells local sweet preserves and other foods which may survive a trip home. This hotel/sweet shop also runs a nearby shop on the main shopping lane which sells local foods, including the very good local capers (pickled along with their leaves, and much more pungent and flavorful than typical bottled capers) and the simple but interesting Sifnos wine. Sifnos is also known for its pottery, and shops in Apollonia and Kamares sell attractive goods in a wide range of prices. Perhaps the most worthwhile souvenir would be a pot (quite affordable) from the potter in Cheronisos, described above.
The Book Shop (To Vivliopoleio), with a store in Apollonia (down the street from the post office) and another in Kamares (at the other end of town from the ferry quay) has books about Sifnos and general books in English and other European languages. It's also the place to go for English (and other European language) magazines and newspapers.
There is a drop-off laundry in the Hotel Anthousa/Gerontopoulos sweet shop building in Apollonia, open most hours.
Sifnos has long had a reputation in Greece for excellent cuisine; but unfortunately, it rarely lives up to it these days of mass tourism, and of imported ingredients and chefs. Good restaurants on the island include Liotrivi in Artemonas: Open year round and offering the most extensive menu on the island, it is a sure bet. The restaurants in Restaurant Row, in Kamares harbor, are also reliably good, and offer variety in style: from fast food, to good local fare, to international (excellent Italian.) On the other side of Kamares Bay, by Aghia Marina, is arguably the most romantic by night Argyris, reputed also, for high quality and service. To Astro and Leonidas in Kastro offer great views and are great places for lunch. The restaurants in Seralia (by Kastro), offer reliably fresh seafood, but they are very seasonal. Good seafood places can also be found in the fishing villages of Faros (for most of the year), and Heronissos (seasonal). Near beaches, the many restaurants at Plati Yialos offer good, family type atmosphere and cuisine; the restaurants at Vathy beach are also good, with traditional menus and good (quiet) ambiance. Off the bus route, if you drive, try the very traditional tavernas in Apokofto bay near Chrisopygi, and in Fasolou beach near Faros. In Kastro, To Konaki cafe/creperie and sweet shop by the bus terminal, has a balcony with good views and traditional sweets; the ekmek, a Greek dessert of Turkish origin, is good here, though very rich. A similar, equally good, and more accessible sweet shop is Gerontopoulos in Apollonia, also by the bus stop. In Artemonas, on the plateia (square), is also the cafe/restaurant Margarita, where you can put together a meal from small plates; the traditional Sifnos chickpea soup, usually made only for Sundays, can be good here. If you are in Apollonia, there are several tavernas, and even funky, nouveau restaurants in the steno to catch a quick lunch or even a leisurely (albeit noisy) dinner during high season. Also in Apollonia, coffee shops, souvlaki stands, and easy breakfast stops abound. Several hotels on the island run full restaurants for guests. Ivariably, these are also open to the public; the quality is usually high, and the views can be breathtaking (look for them in Kamares, Petali, Plati Yialos, etc.)
Kamares, Apollonia, and Artemonas all have grocers and bakeries. Most of the beach resorts and small villages, have at least one small shop which sells a limited range of food items and notions. The two pharmacies of the island are both in Apollonia; you will find them next to, or very near the island's three Banks.
In Kamares, the ferry port, there's a pretty stylish pub and feet-in-the-sand bar, with cocktails, lounge music, yacht crowds, and the young and hip. It is located at the farthest point of the bay, walking down from the ferry dock all the way, to where the beach begins.
Aside from Kamares, most cafe/bars are in Apollonia. There are a few on the main road that goes past the National Bank, which have balconies or terraces with good views; and more on Apollonia's main street (known as the Steno), a couple of which are of the boomboom-music-dim-lights variety. A more civilized option on that street is Argo, which has pleasant outdoor seating and well chosen recorded jazz and classical music. In Kastro Dolci, by the bus terminal, is a high end bar/creperie shop with international feel, easy music, and great views.
For the gorgeous, the young, and the energetic, there is the all day, and all night beach club at Lazarou. There, you can also experience a heavenly swim off a rocky, but gently descending beach. You can reach it by a short walk, over the hill, past the bus terminal at Plati Yialo; or you can drive to it over a winding, narrow, scary but paved road, starting at the farthest end of the Plati Yialo main drag.
The Petali Village Hotel  Ano Petali tel: +30 22840 33024 fax: +30 22840 33391 email: email@example.com or firstname.lastname@example.org. The hotel is perhaps the highest-class hotel on the island, with rooms, suites, and one self-catering apartment set on a hillside with a terrific view on the footpath halfway between Apollonia and Artemonas. (There's also access by car via a roundabout road that ends up in a parking lot behind the hotel.) It has a restaurant, open only in high season, and a pool. Rates are high for Sifnos but so is the hotel's quality, and they sometimes offer significant discounts out of season.
If you're keen on meeting other tourists, Vathy, considered the best beach on the island, is a growing resort with modest studio hotels and an extensive new fancy resort complex, the Elies. Plati Yialos, the most built up beach, has numerous places to stay.
Kamares has good accomodation and is a good option to stay because there are good options for eating and having a drink in the evening and it's close to the ferry.
There are several places to rent rooms outside of Kastro. Some have patios and shared kitchens.
There are pay camp sites at Kamares (Camping Makis) and Plati Yialos (Camping Plati Yialos.)
Almost all boats leave from Kamares, going in summer daily or almost daily back to Piraeus or onward to Milos, with less frequent boats to other islands in the Cyclades group. There are several travel agents selling boat tickets in Apollonia and in Kamares.