Kosterhavet National Park: A guide to Sweden's only marine wilderness

Sweden's national parks are often associated with deep forests or dramatic mountain ranges. But in the west, right on the border with Norway, lies a completely different kind of wilderness. Kosterhavet is the country's first marine national park, and it is here that the greatest biodiversity is found below the surface. But for those of us who prefer to keep our feet on dry land, the islands of North and South Koster offer a hiking experience that is unique in its kind.

Our own CEO, Anders Mickelsson, recently took the boat out for a day trip. His visit focused less on technical shell gear and more on the good life in the archipelago – a reminder that a visit to a national park doesn’t always have to involve heavy lifting and lactic acid. According to Anders, a stop for lunch at Strandkanten on Nord-Koster is an absolute must if you want to experience that genuine Bohuslän feeling between the turns on the trails.

In this guide, we go through how to get the most out of Kosterhavet, whether you are planning a multi-day hike with a tent or a relaxed boat trip with a focus on swimming and good food.

More than just hiking: Experiencing a marine national park

It's easy to fall into the trap that "visiting a national park" must mean checking off a certain number of kilometers on a trail. But Kosterhavet requires a different mindset. Here, it's as much about the journey there – the boat trip from Strömstad through the archipelago – as it is about the actual steps you take on the islands.

Visiting Kosterhavet is about understanding the interplay between land and sea. You can hike on the polished granite cliffs, take a dip in the salty water at one of the many sandy beaches, and then end the day with smoked shrimp at a local tavern. It is an accessible form of wilderness that welcomes both the experienced hiker and the family with children looking for a memorable day trip.

Tips for the day trip

If you’re like Anders and want a more relaxed day trip, Nordkoster is a great choice. The island is more rugged and smaller than its southern neighbor, making it perfect for exploring on foot over a few hours. After seeing the lighthouses on the Kostersundet Strait, head to the Strandkanten restaurant. It’s the kind of place where time slows down and the food tastes just as fresh as you’d hope when you’re in the middle of a marine reserve.

Nordkoster vs Sydkoster: Which island should you choose?

The islands differ markedly in character, and your choice should depend on what you want to get out of the day.

Nordkoster: The barren wilderness

Nordkoster is smaller, car-free and has a more raw, exposed nature. Here you hike across vast fields of shingle and heather heaths. The terrain is at times uneven, but never particularly difficult. This is where you will find the most dramatic views of the open sea. For those who appreciate geology, the shingle fields at Valfjäll are a must – a reminder of the enormous power of the ice sheet.

Sydkoster: The lush idyll

Sydkoster is larger and much more leafy. Here you will find deciduous forests, flowering coastal meadows and long, child-friendly sandy beaches such as Rörvik and Kilesand. Sydkoster is also easier to get around by bike, as the road network is more developed. Here you will also find the Kosterhavet visitor center at Ekenäs, which is the perfect starting point to learn more about life below the surface before you lace up your boots.

Equipment for coastal hiking

Although the Koster Islands do not offer alpine altitudes, the marine climate places specific demands on your equipment. The biggest challenge is often the wind. Out in the ocean there are few places to take shelter when the west coast wind picks up.

1. Shell clothing and layering

A technical shell jacket is your most important defense against the salty sea breeze. Even on a sunny day, the wind can be chilly, and when you stop for a break, you'll quickly cool down if you're sweaty.

As the sun sets over the Kosterfjord, the temperature drops quickly. For evenings on the rocks or in the tent, a light down jacket or quilt is invaluable. If you’re wondering what type of insulation is best for humid coastal environments, we recommend our complete guide to down in sleeping bags , where we delve into the differences between different down types and how they handle moisture – a critical factor when sleeping near the sea.

2. Foot covering for granite and sand

Many people make the mistake of wearing shoes that are too soft on Koster. The granite is hard and the pebble fields can be prone to twisting. We recommend a sturdy hiking shoe or a light boot with good grip. The sole must be able to grip both dry and wet rocks. If you plan to walk the longer trails on Sydkoster, your feet will thank you for the extra support.

3. Packing for the day trip

A 20-30 liter backpack is plenty for most island trips. Focus on bringing enough water (it can get very hot in the open fields), swimwear, and a sturdy first aid kit.

Overnight stay in the national park

Kosterhavet has special rules for camping to protect the sensitive nature. It is not allowed to camp anywhere according to the right of public access. On North and South Koster, camping is only allowed at the designated campsite at Vettnet on North Koster during the period 1 July to 15 August. The rest of the year, specific rules apply to different parts of the park.

Ask yourself: Do you really need to camp to get the experience you're looking for? Many people choose to stay in guesthouses or rent a cabin and do day hikes with a light pack. This saves on legs and gives you more time to actually enjoy the surroundings. But if you choose a tent, make sure you have a sleeping pad with good insulation. Ground chill from the rocks can ruin even the best summer night.

The pragmatic hiker's checklist for Kosterhavet

1. Check the boat times: The Koster boat leaves frequently from Strömstad, but if you miss the last trip home, it will be an expensive taxi boat.
2. Pack some wind protection: A small tarp or just a good shell garment makes your lunch break on the rocks much more pleasant.
3. Respect the zones: Keep an eye out for bird sanctuaries and seal sanctuaries. In a marine national park, these boundaries are often drawn in the water, but affect where you can go ashore.
4. Shoes for the terrain: Leave the flip-flops in your bag until you reach the sandy beach. The granite requires proper soles.
5. Dare to be a tourist: National parks are about protecting nature, but they are also there for our sake. Eating a good lunch at Strandkanten is just as much a part of the experience as seeing rare lichens on Nordkoster.

Summary: The balance between adventure and recovery

Kosterhavet is a reminder that wilderness doesn't have to be difficult to access or require weeks of planning. It's a place where you can challenge yourself with a hike across the shingle fields in the morning and sit with a cold drink by the Kostersundet strait in the afternoon.

As we always say here at HikingStore: The best gear is the one that actually gets used and makes your experience better, not heavier. Whether you're aiming to see the seals in the outer archipelago or just want to find the perfect swimming cliff, it's all about being prepared for the weather without carrying unnecessary pounds.

Are you planning a trip to another Swedish national park? Don't miss our guides to Skuleskogen National Park or the magical Tiveden .

See you on the trails (or on the beach)!

Meta description (to Anders): Are you planning to hike in Kosterhavet National Park? We guide you to the best trails on North and South Koster, give tips on equipment for coastal climates and share our best local spots like the Strandkanten restaurant. Discover Sweden's most beautiful marine wilderness with HikingStore.