Sunny Beach pretty much shuts down for winter. The season is often divided into three:
Low season from beginning of May to mid-June, September
Middle season: mid-June to (mid-)July, mid-August to September
High season: (mid-)July to mid-August, or even until end of August
However May is probably not recommended as even if some hotels are open, many restaurants etc. apparently don't open until June. Same goes for the end of season.
Sunny Beach is usually entered via [wiki=99d90a58f2ae7d2ef9396128341b94d0]Burgas[/wiki] airport [http://www.burgas-airport.bg/Home/tabid/36/language/en-US/Default.aspx], which lies about 25km from Sunny Beach. There are domestic and international flights to about 116 destinations in 33 countries, by more than 69 bulgarian and foreign airlines.
International road I-9 (Burgas - Varna) is passing next to the resort.
Sunny Beach is not very large so you can cover it mostly on foot. The main beach strip with the beach bars and shops is about 2.5km long. As the shops, bars, and restaurants are mostly quite alike and the main areas of interest are pedestrians-only anyway there's little need for covering longer distances apart for just the fun of it.
There are number of buses between Sunny beach and nearby settlements. Routes, timetables and prices are available [url=http://www.sbavto.com/en/index.php?option=com_content&view=article&id=45&Itemid=71]here[/url]. For short distances (e.g. to [wiki=9fd91eb896d8f33ff25dc06651741a1b]Nesebar[/wiki]) the ticket fee is 1 BGN (as of 2013). Buses are quite crowded during rush hours. Many of the buses have a section for people with strollers so using buses is a good choice for people with children as well.
Reaches only part of the boulevard and runs only rather short distances (e.g. the train from [wiki=9fd91eb896d8f33ff25dc06651741a1b]Nesebar[/wiki] takes you only to the southern part of Sunny Beach from where it is still 4km to the center). No regular timetable, runs when it's full. Can be a bit of a wait. There are multiple routes, so make sure if the train you see is the train you need. Ticket fee is 3 BGN in one direction (as of 2013).
Not very useful in Sunny Beach. Distances are small, the main streets are pedestrian only and traffic in Bulgaria is rather dangerous. The streets in the main resort area are also often dead ends or just loops so you cannot really get anywhere unless using the main road.
Not very fast but you travel in style.
Regular fee is 3 BGN/km (as of August 2012). However there might be some scammers, so check the tariff before you enter the cab and keep an eye on the counter.
There is boat connection between Sunny Beach and [wiki=9fd91eb896d8f33ff25dc06651741a1b]Nesebar[/wiki]. The boat docks at the central pier and travels every 20 minutes.
There are couple of dive shops in [wiki=9fd91eb896d8f33ff25dc06651741a1b]Nesebar[/wiki] offering courses and fun dives in the Black Sea.
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* Diving center located in the city of Saint Vlas, north of Sunny Beach