For international flights, Royal Air Maroc has an office in the centre of town.
There is a ferry service called the Elobey that runs weekly between Malabo and Bata, departing Friday at 6am and returning on Sunday. It is best to visit the New Port a few days before you intend to leave to try to buy tickets and confirm departure times. Expect to pay around CFA33,000 one way. The journey takes five to 10 hours, depending on the sea and the weather.