Ferry crossing
Direct ferries run from Krabi Town's Chaofa Pier and Ao Nang to Tonsai Pier on Phi Phi Don, taking around 1.5-2 hours depending on the boat and conditions. Multiple daily departures run in high season (roughly November-April); services thin out and can pause in rough weather during the June-October monsoon.
Day tour vs one-way ferry
If you just want to see Maya Bay and Phi Phi's cliffs for a day, a organised speedboat day tour (covered in our Phi Phi Islands guide) is usually the better-value option, since it bundles the return trip with stops and guiding. A one-way ferry ticket makes more sense if you're planning to stay overnight on Phi Phi, or continuing onward from there to Phuket.
Onward from Phi Phi
Phi Phi also sits on the Krabi-Phuket ferry route, so if you're island-hopping, it's easy to break the Krabi-to-Phuket journey with a night or two on Phi Phi in between — see our Krabi to Phuket guide for that connection.