There is no public bus service on Bonaire. However, dive operators will haul you wherever you need to go. You can see all of the island in one or two days of driving, so you might consider renting a car for just that period. Many places to stay offer packages with a car thrown in cheap.
Most international car-rental firms are at the airport. The main local operator is AB Carrental (599-717-8980; www.abcarrental.com).
There are a couple of gas stations in Kralendijk, including Gas Ekspres (599-717-7171; Kaya Tribon; 7am-10pm).
Taxis from the airport to hotels in Kralendijk cost US$8 to US$18 depending on which end of town you’re going to. A taxi to any place on the island costs no more than US$25.