Cancún International Airport (CUN) is about 100km north and the obvious arrival point. Pre-arranged shuttles and private transfers run for about US$60–90 one way; the ADO bus from the airport is much cheaper but drops you at the highway, requiring a taxi from the junction.
Driving the Highway 307 from Cancún or Tulum is straightforward — Akumal is signposted from both directions and the village turnoff is on the east side of the highway. Most visitors rent a car, since exploring nearby cenotes and ruins is much easier with one.