This paper explores issues relating to defining environmental damage in a potential liability regime for deep seabed mining activities in the Area. The paper reviews approaches to environmental damage in existing liability regimes and processes established in international law in relation to other activities and areas, with a view to providing information and examples that might be useful to further consideration of the definition and valuation of environmental damage arising from deep seabed mining activities. It also identifies some of the considerations relating to mining activities in the Area that pose specific challenges for addressing the definition and valuation of environmental damage.