The scope of the issue will be based on achievements of research groups involved in the FP7 project “Design for Ship Safety in Extreme Seas” (Acronym “Extreme Seas”, http://www.mar.ist.utl.pt/extremeseas/) in view of completeness of the project on 30 April 2013. The project addresses assessment of extreme sea states, and ship behavior in such sea states. The project studies physical and statistical properties of extreme waves, and develops advanced numerical and physical simulation models for wave-structure interaction. One of the main objectives of the project is to develop warning criteria for marine structures against extreme sea states and extra-ordinarily large waves. The project involves 11 European teams working in academia, scientific research and industry: Det Norske Ver1tas AS (Norway), Instituto Superior Tecnico (Portugal), Germanischer Lloyd AG, Technische Universitaet Berlin (Germany), Meteorologisk Institutt (Norway), Universita Degli Studi di Torino (Italy), Institute of Applied Physics (Russia), Canal de Experiences Hidrodinamicas de el Pardo (Spain), Meyer Werft Gmbh (Germany), Estaleiros Navais de Viana do Castelo SA (Portugal), Universitaet Duisburg-Essen (Germany).