The Stagecoach buses offer good and regular service around the entire island - to go completely around takes some 30-40 miles and about two hours. Most one way fares were 2.3o pounds, so you are better off buying a DayRover pass for 4.20 pounds which gives you unlimited use of the buses for the day. That is great for when the weather is threatening, enabling you to trade a wet, bleak mountain trek for a warm tour around the island.
The main way of getting to Arran from mainland Scotland is by Caledonian MacBrayne ferry from the Ayrshire town of Ardrossan. There are several daily crossings and the ferry runs year round.
Its a roll on roll off car ferry and to take a standard vehicle is approx £59 return [summer 2010] and £9 per passenger [whether on foot or in a vehicle]
There are two ways to get you and your car onto Arran and both are operated by the folks at Cal/Mac. The main ferry runs from Ardrossan - direct connection by train to Glasgow Central from here - on the mainland over to Brodick. This ferry runs year round. The other ferry, running from Lochranza to Claonig - nothing more than a ferry landing - on the Kintyre Peninsula a few miles south from Tarbert, only runs during the summer months. Plus, this ferry is a much smaller affair and its service can be disrupted with bad weather.
There is a bus station once you step off the main ferry into Brodick. They are scheduled to meet you off that ferry and take you to various parts of the island. Generally, these buses only operate around ferry arrivals and departures. Although there are bus stops around the island, it is common to wave a bus down anywhere. But there are other ways of getting from A to B.
A postbus, in the form of a Royal Mail van, is available with its own timetable. This is obviously a smaller vehicle and will hold around 8-10 passengers, as well as the mail load.
There are also taxi companies that can meet you at the bus station or anywhere else on the island.
The bus I usually get (Brodick to the next village, Corrie) costs me £1.20 for a single ticket. A taxi for the same ride cost me £7.00. Quite expensive, but a necessity if you don't have a car.
Getting to Arran is simple, ferries operate all year round from Ardrossan on the mainland to Brodick, and from Claonaig to Lochranza. Ardrossan ferry terminal has a mainline railway station that conects to Glasgow central and other Scottish routes, and plenty of parking spaces, although the ferries take cars too. An adult return fare was roughly £20 in the summer of 2004, but group discounts are available if more than 12 people are trravelling. The crossing takes about an hour.