A large fjord system stretching from the north coast of Sjaelland down to the city of Roskilde. Easily accessible many places by car or public transport, and approachable from cities Roskilde, Jyllinge and Frederikssund riding a bike.
The fjord is brackish and known for its cold season fishing and even has good winter fishing when there is no ice. In the garfish season (May and June) there's a great abundance of these slim fish, and in the summer and autumn you can sometimes find large schools of mullet grazing in the warm water of the fjord.
Most of the fjord system is well sheltered and even fairly hard winds will not stir it much. You can almost always fish the banks with off shore wind, and in many cases also fish where a light wind is on or along the beach depending on your temper and your casting skills.
The fjord is large and has easy car access many places, and buses serve all major and medium size cities along the coast. Jylling and Frederikssund can be good starting points. From these cities as well as Roskilde itself you can ride a bike to many good locations on the fjord.