The river at Calabar forms a natural harbor deep enough for vessels with a draft of 6 metres (20 ft).

The tropical rain forest in the Calabar River basin is rapidly being destroyed, and pollution is decreasing fish and shrimp catches in the estuary.

[citation needed] The region has a rainy season from April until October, during which 80% of the annual rain falls, with peaks in June and September.

[citation needed] Drainage is poor, so the basin is subject to flooding, gully erosion and landslides.

[8] Akwa Akpa (Duke's Town) became a center of the trade where slaves were exchanged for European goods.

[9] Due to public petitions against slave trading, the British House of Commons held a hearing on the 1767 massacre in 1790.

[17] Calabar today has regained its importance as a port with the completion of roads providing good access to southeastern Nigeria and western Cameroon.

Industries include sawmills, a cement factory, boat builders and plants to process rubber, palm oil and food.

[1] The development of the port, and the neighboring Calabar Free Trade Zone and Tinapa Free Zone & Resort has been held back in recent years by bureaucratic problems, and also by poor power supply, poor roads and lack of dredging of the shallow Calabar River channel.

Much has now been replaced by agriculture, road construction, forestry, industry and housing for the growing population of Calabar.

[citation needed] A study of changes in land use in the Calabar river catchment between 1967 and 2008 showed that the area covered by high forest decreased by almost 30% during that period.

[20] Urban pollution and oil exploration activity in the near shore area both threaten the ecology of the estuary, greatly reducing the numbers and diversity of the species that provide food for shrimps and fish.

[22] The rate of accumulation of hydrocarbons was greater in the wet seasons, probably because of higher levels of contaminated material washed from vehicle maintenance shops by the torrential rains.

[citation needed] The state government faces a serious challenge in accommodating this growth while maintaining income levels and avoiding ecological disaster.