This report addresses the question of Nigeria's fragile coastal areas. Using a consistent valuation methodology, it estimates the cost of coastal degradation in three Nigerian states: Cross River, Delta and Lagos. The results are striking: in 2018 alone, floods, erosion and pollution in these three states cost society US$9.7 billion, or 2.4 percent of the country’s GDP. As this estimate covers less than a half of the country’s coastline, the total cost of coastal degradation in Nigeria is certainly higher.