The big excitement of Calais is getting into the marina. First, you have to deal with tidal streams and sandbars outside. Then you have to watch for ferry traffic and get the entry lights.
The marina is inside a sill to keep the water deep when the tide goes out. This is crossed by a bridge that opens at set times once there is enough water over the sill. Although a variation of this scheme is common along the French side of the English Channel, it was our first. We arrived before the bridge opened and had to take a mooring buoy to wait.