ABSTRACT Cooperative oil spill Ecological Risk Assessment (C-ERA) is a preparedness tool that seeks consensus-based decisions regarding potential spill and spill response impacts. The established US Coast Guard ERA approach has generally used 1–2 multi-day workshops, several weeks apart, to identify and work through key issues. In New Zealand (NZ), funding limitations required a faster approach. This paper describes the advantages and disadvantages encountered during a modified 1-day version of the ERA conducted for the Fiordland region. Fiordland is a highly valued and remote National Park and World Heritage Area of 1.25 million Ha, with ∼200km of exposed coastline, and ∼1800km internal coastline including 15 main fiords. The unique climate, topography, bathymetry and oceanography, in addition to limited access and infrastructure, make marine pollution response inherently difficult. Recent increases in cruise ship and commercial maritime activity has increased the spill risk, especially for fuel oil. Information previously gathered from interest/advocate groups and government agencies was used to identify priority resources and summarise the spill risk. Then, at a 1-day workshop, six experts in Fiordland ecology, spill response and ERA processes defined the most ecologically important areas and priority resources across the region, and their susceptibility to oil. Levels of concern were applied to each area and identified resource, and the preferred response options and their feasibility defined. Outputs were presented on a series of planning maps and site sheets completed for each priority area after the workshop which were circulated for stakeholder review. The approach enabled a defensible response plan to be generated quickly and cheaply. It secured input from agencies who would not have participated had a greater time input been required and generated a concise document for public consultation and a template for ongoing refinement. The success of the approach was due largely to the high level of trust between scientific and response agencies in NZ, and a shared desire to rapidly improve response planning outcomes. Disadvantages were the inability to fully review and include all available technical information, limited public consultation, and tight time pressures. Examples are given of the benefit of the plan following its use during a recent spill of marine diesel.