Recent international tsunamis, including the 2011 Tohoku Tsunami, Japan, and the 2015 Illapel Tsunami, Chile, have highlighted the potential for impacts on the built environment. International research in the tsunami impacts domain have been largely focused towards impacts on buildings and casualty estimations, while only limited attention has been placed on the impacts on critical infrastructure. New Zealand, a developed and tectonically active island nation in the South Pacific, has a large amount of coastal infrastructure exposed to many local, regional and distal source tsunamis. To effectively manage tsunami risk for New Zealand critical infrastructure, including energy, transportation and communications, the vulnerability of infrastructure networks and components must first be determined. This research develops relevant asset vulnerability, functionality and repair-cost functions based on international post-event tsunami impact assessment data from technologically similar countries, including Japan and Chile. Utilising these functions within a New Zealand based framework allows for cost benefit analyses, determining effective tsunami risk management strategies and mitigation options for exposed critical infrastructure.