Connectivity can be defined as the physical or ecological conditions that allow living organisms and non-living material to move between, or influence, habitats, species populations or assemblages that are intermittently isolated in space or time. This document provides an introduction to two forms of connectivity, functional and structural, and discusses these in terms of transboundary considerations. There are a number of other forms of connectivity, such as genetic connectivity, all of which are interlinked within the ocean system and can be transboundary in nature and vary in scale across the ocean. This presents an important challenges to planning (and management) processes, including regional-scale planning processes such as Regional Sea Programmes. This document therefore provides an introduction to connectivity in the marine environment in a spatial planning context. Through this, the first steps are taken in terms of in helping states assess the relevance of the ABNJ in their planning processes.