Anei Kankō and Hateruma Kaiun together have four departures daily from Ishigaki harbor. If you buy a round-trip ticket, be sure to catch the same operator's boat on the way back. Travel time is 60 minutes.
There are no buses or commercial car rental companies on Hateruma, so for trips beyond the village, rent a bicycle or moped. Some guest houses like House Minami offer car rental service to staying guests for a fee and even to non-staying visitors for a slightly higher fee but bicycle is probably the best way to enjoy Island life and the 'middle-of-nowhere' atmosphere.
Hateruma's local specialty Awanami (泡波) makes its way from the distillery to the local stores only sporadically, and the islanders usually buy it all up within hours. So if you come across anything larger than the tiny 100ml bottles, grab it. Fuka Shōten (冨嘉商店) is a good place to look.