Even the history of this is fascinating. This is the "Moses Bridge", and it's a renovated part of the old dyke system that was used to prevent attacking armies from getting in - because the dykes and levee's had blocked the sea so effectively, they realised they could stop attackers by... flooding them out. Literally.
When it came to renovate this area, they wanted to provide access without denigrating the fact it was an old defensive structure, hence this unique sea-level bridge.