This article presents a step-by-step procedure for estimation of the joint distribution of N-year maximum significant wave height, individual wave and crest heights, and total water level, accommodating the effects of directional and seasonal variation, surge and tide. The approach is based on non-stationary extreme value analysis of peaks over threshold incorporating careful uncertainty quantification, and is illustrated for a North Sea location using hindcast data. The article further provides a brief overview of the development of a regulatory framework for specification of design conditions for total water level over the past half century.