The most accessible day trip from Port Harcourt is the ferry crossing to Bonny Island, roughly 40 minutes by speedboat from the Bonny Waterside. The island has an interesting history as one of the major slave-trading ports of West Africa in the eighteenth century, and it retains some colonial-era architecture alongside the massive LNG export facility that dominates modern Bonny. Finima Nature Park on the island's southern tip offers guided nature walks and birdwatching.
Okrika, accessible by boat north along the Bonny River, is a historic Ijaw town built on islands in the delta. The journey through the waterways is the attraction as much as the destination itself — the landscape of creeks, mangroves, and stilt villages is striking. In Okrika, the church of St Peter is an early colonial-era building worth seeing.
Obudu in Cross River State is a longer drive — four to five hours on good roads — but the Obudu Mountain Resort sits at altitude in the Sankwala Mountains and offers a dramatically different climate from Port Harcourt's lowland heat. It is better as an overnight trip than a day trip.