Over the past decade, there has been global expansion in the advancement of underwater cleaning technology for ship hulls. This methodology ensures both diver safety and operational efficiency. However, recent attention has been drawn to the harmful effects of ship hull-cleaning wastewater on marine animals. It is anticipated that this wastewater may have various impacts on a wide range of organisms, potentially leading to populationand ecosystem-relevant alterations. This concern is especially significant when the wastewater affects functionally important species, such as aquaculture animals and habitat-forming species living in coastal regions, where underwater cleaning platforms are commonly established. Despite this, information on the ecotoxicological effects of this wastewater remains limited. In this mini review, we discuss the adverse effects of wastewater from in-water cleaning processes, as well as the current challenges and limitations in regulating and mitigating its potential toxicity. Overall, recent findings underscore the detrimental effects posed by sublethal levels of wastewater to the health status of aquatic animals under both acute and chronic exposure.

Introduction
Measured components in hull-cleaningwastewater samples
Contamination pathways
Effects of hull-cleaning wastewater onmarine organisms
Challenge and limitation
Acknowledgement
References

• Jae-Sung Rhee(Department of Marine Science, College of Natural Sciences, Incheon National University, Incheon 22012, Korea, Research Institute of Basic Sciences, Core Research Institute, Incheon National University, Incheon 22012, Korea, Yellow Sea Research Institute, Incheon 22012, Korea)
• Seong Hee Mun(Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje 53201, Korea)
• Jee-Hyun Jung(Risk Assessment Research Center, Korea Institute of Ocean Science and Technology, Geoje 53201, Korea, Department of Ocean Science, Korea University of Science and Technology, Daejeon 34113, Korea) Corresponding author