There is daily ferry service between Lahaina on Maui, and Manele Bay on Lanai, with Expeditions Lanai Ferry. The 9-mile crossing costs $60 round-trip and takes about 45 minutes or so, depending on ocean conditions (which can make this trip a rough one).
Molokai Ferry offers ferry service four times per week between Lahaina on Maui, and Kaunakakai on Molokai. Check their website for available travel dates. Travel time is about 90 minutes each way, and the one-way fare is $68.27. Reservations are essential. All voyages may be subject to cancellation if a minimum of 20 confirmed passenger reservations per voyage leg are not received 48 hours in advance.
Expeditions Lanai Ferry. 800/695–2624; www.go-lanai.com.
Molokai Ferry. 808/667--5553; www.molokaiferry.com.