Exploring the islands by boat can be arranged via hotels and the national park office. A 12-person boat costs around 2,200,000d to 5,000,000d per day depending on stops wanted. Local fishermen also offer excursions, but be sure to bargain hard.
Motorbike & Bicycle
This is one of the best places in Vietnam to ride a bike, with little traffic, no pollution and good surfaced roads. There's only one main road, connecting the airport in the north to Ben Dam in the south via Con Son town.
Most hotels rent motorbikes for around US$6 per day. Bicycles cost around US$2 per day. There are good coastal cycling routes, such as from Con Son town to Bai Nhat and on to the tiny settlement of Ben Dam. The ups and downs are pretty gentle. Be very careful of the high winds around Mui Ca Map (south of Con Son town); locals have been blown off their bikes during gales.
Con Son Island has several taxis. However, as metered rates are high negotiate hard for a fixed-price rate to destinations outside Con Son town.