The most common way of getting to Cape Cod—and this is immediately apparent, especially on weekends—is by car. Without traffic, the drive from Boston to the beginning of the Cape is only two hours. During the summer it is best to leave early and be prepared to sit in traffic. Parking is also a challenge near the beaches.
Busses leave from Boston’s South Station and make several stops between there and Provincetown. Round trip to Provincetown costs about $50-60 and takes about four hours one-way (although busses are as subject to traffic as cars are).
The MBTA runs a commuter ferry between Boston and Hull on the north shore of the Cape, which costs $12 round trip.
Ferries run between Boston and Provincetown and are a fast option if you want to skip the bulk of the cape. They take about an hour and a half and cost $70-80 round trip.