Despite the best efforts of the South Downs Campaign, the South Downs National Park does not include any marine areas. Nonetheless, it does have a marine boundary at a number of places east of Brighton, the most significant being the Heritage Coast between Seaford and Eastbourne. The influence of the sea is also an important feature of the National Park along most of its length.
The South Downs Network has engaged with the establishment of marine conservation zones in Sussex but remains to be convinced as to how effective the process will be in delivering marine conservation. It’s response to the recent consultation can be found here.