This is not a guide for paddling in general, but rather information for foreigners going on a paddle trip in Denmark.

Access to costal areas

According to the law for environmental protection the public has free access to beaches, forests, uncultivated land and the open country. The exact meanings of these areas are further specified, but in this context we will focus on the beach. The beach is defined as the area from the low tide mark to the zone of coherent land vegetation. This can mean anything from a 1m wide beach to a 400m wide beach. On the beach one is free to walk, bath and make short stays. A short stay is defined as a stay no longer than a day(which could be a night). If staying on a private beach, you must be at least 50m away from inhabited houses. One is also allowed to have a boat lying on the beach during the stay.
As a consequence of this law, you can pull your kayak ashore almost anywhere to rest and eat your lunch.

Camping

Tenting is not legal on the beach. The exact interpretation of what tenting means is somewhat unclear. When asked, the Danish Forest and Nature Agency has provided various answers. One thing is clear though; Sleeping next to ones kayak on a sleeping pad in a sleeping bag is certainly legal. Likewise most would agree that sleeping under a tarp is legal. Sleeping in a bivybag is most likely legal, while it's properly illegal to use a tarp-tent. Using a regular tent is not legal.

In May 2004 the Danish Forest and Nature Agency has provided an official answer to a question posed by Poul Henrik Harritz, the president of The Danish Society for the Conservation of Nature, regarding the law for environmental protection and its interpretation as related to sleeping on the beach. 
Roughly translated their answer reads:
It is the opinion of The Danish Forest and Nature Agency, that it isn't legal to build a bivouac, a construction with a tarp and two paddles or similar more or less ad hoc constructions which substitutes tents. A sleeping bag with or without a special cover is legal though. 

In other words. It is legal to sleep in a bivybag on all danish beaches(on private beaches, you must stay at least 150m away from buildings). As an example, the bivybags produced by Integral Designs without poles are definitely legal. 

One should realize that these rules are not made with the humble, low impact, always on the move seakayaker in mind. Outdoor activities, involving primitive tenting on the beach is very rare in Denmark. As a consequence, the vast majority of Danes find it curious and even admirable, when some seakayaker is staying on their local beach for the night. Of course one should choose a campsite, which is a bit out of the way. If that isn't possible, then consider postponing putting up the tent until its getting dark. 

To summarize: Unauthorized camping (wild camping) in tent is not allowed in Denmark. This doesn't mean people aren't doing it anyway and in 99.99% of the cases they have no problems doing so. 

There are a couple of legal alternatives to wild camping: 

Ask for permission: The problem with this solution is that it's often far from obvious whom to ask. Should you however track down the right person, then you'll hardly ever be turned down.

Official primitive tent sites: During the last 10 years, a net of around 700 tent sites has been established all over the country. The sites are only open for people arriving by primitive means like hiking, paddling, riding and bicycling. Using these sites is highly recommendable. Unfortunately there aren't many sites close to the coast. You find more information in English and German at: teltpladser.dk

Commercial campsites: A large number of commercial campsites are located close to the shore. You'll most likely feel a bit out of the place, with your little tent and smelly polypros among caravans and mobile homes. On the other hand, it might provide an interesting view into a different kind of outdoor culture.

Notices to Mariners

The weekly publication Notices to Mariners(Danish: Efterretninger for Søfarende) is available online. The most useful information for seakayakers provided in here, is the list of planned military shooting exercises. The text is only available in Danish.

Maps, Charts and Pilot books

Kort og Matrikelstyrelsen(KMS) is the Danish authority responsible for both topographic maps and sea charts. KMS used to run an online shop, where the various maps were sold. The shop is closed now and the online selling is done by two different companies: Nordisk Korthandel sells topographic maps while Schultz sells sea charts.

When paddling in Danish waters, you can usually get by using only topographic maps in scale 1:100000 or 1:50000. You should however bring sea charts, if you plan to paddle the areas listed below.

Notice that only sea charts marks areas with restricted admittance due to bird and seal sanctuaries. Most of these areas consist of small islands with no admittance from early spring to midsummer. Yellow warning signs are placed in these areas. Likewise only sea charts marks military shooting ranges.

KMS offers two cdrom products, both useful for planning: Det Levende Danmarkskort contains a complete topographic map scale 1:50000 while Det Levende Søkort contains all Danish sea charts. Both products are quite affordable. Even though the text in the programs is written in Danish, foreigners should have no problems using the core sliding map function.

KMS publishes a two volume pilot for navigating in Danish waters. As much as it's recommendable to study pilot books before visiting foreign countries, this really isn't necessary for Denmark. Only a minority of Danish seakayakers knows of the existence of these pilot books.

Military shooting ranges:

There's a number of shooting ranges in Denmark. You'll find a detailed description in the appendix Oversigt over forsvarets skydepladser of the first issue of Notices to Mariners every year. Have a look at the map showing the positions. The most active ranges are EK R 33/D 80/D 81 at Blåvand, EK R 11/12/13/D 50/D 51/D 53 at Sjællands Odde and EK R 18 at Jærgerspris. 
An active shooting range is marked by a bright flashing light.

Getting help

Cell phone coverage is good in most places. Call 112 in case of an emergency.

Weather forecasts

The Danish weather authority is the Danish Meteorological Institute(DMI). They have information available in English. DMI provides a telephone-service you can call for an updated weather forecast. Call +45 1853 for information in Danish and +45 1854 for information in English or German. A detailed weather-forecast in Danish is broadcasted five times per day at 5:45, 8:45, 11:45, 17:45 and 22:45 at the frequences MW 1062kHz and LW 243kHz. Immediately after the 17:45 weather forecast, the daily notice to mariners is broadcasted (in Danish). The short program provides a terse update on changes in aids to navigation and lists the shooting ranges that will be in use the following day.
But what's the weather really like in Denmark? That question is best answered by Technical report 99-13 on Observed Wind Speed and Direction in Denmark published by DMI. The report contains an excellent introduction to the danish weather along with statistics on wind observation for a range of years. The report is written in both danish and english.

The Do's and Don'ts of kayaking in Denmark

There really aren't any "Don'ts" to report. The absence of strong tide (not counting Vadehavet) makes Danish waters predicable and the lack of rocky cliffs makes landfall possible everywhere.

Crossing Storebælt(Great Belt) is considered an advanced trip, since you will be crossing the international shipping lane Route-T(the transit route) and experience moderate amounts of current. Do bring sea charts. Same goes for crossing Øresund(The Sound) between Denmark and Sweden.

There's intense ferry traffic between Helsingør(Denmark) and Helsingborg(Sweden). Likewise you should be aware of the High-speed ferries, going between Århus/Sjællands Odde and Ebeltoft/Sjællands Odde. The sea charts marks their sailing routes.

A Trip around the Danish Coast

The waters around Denmark are divided into the inner and the outer waters. The outer waters consist of Skagerak and the North Sea bordering the exposed western coast of Jutland. The inner waters consist of the rest.

Vadehavet, marked by the yellow color, is the area between the German border and Skallingen, some 15km north of Esbjerg. Vadehavet is characterized by shallow water and tide. The tidal difference is in the order of 1.5meters. You should bring a sea chart when paddling in this area.

The western coast of Jutland, marked by the red color, is a fully exposed open beach. You should expect quite some surf action here. Towards Grenen, the tip of Jutland, the tidal difference decreases to around 40cm.

The inner waters are sheltered and the tidal difference is almost unnoticeable. A number of places, marked by the green color, are known to be very sheltered. Beginners should consider these areas first.

Marine Authorities in Denmark

Søværnets Operative Kommando - The Navy's Operational Command, coordinating SAR operations. 
Farvandsvæsenet - The Royal Danish Administration of Navigation and Hydrography. They publish Navigation through Danish Waters. 
Søfartsstyrelsen the Danish Maritime Administration under the Ministry of Economic and Business Affairs.