Slide 1


open water swim event

Rondje Pampus is an unique open water swimming event organized annually to draw attention to the vulnerable nature in the IJsselmeer region of The Netherlands. Swimming in open water around Fort Island Pampus is spectacular for both recreational and competitive swimmers. A sporting challenge while enjoying the vastness around you, of wind, waves and water. Because you truly experience nature in open water!

Participants in Rondje Pampus contribute part of their entry fee to a good nature cause. Last year, for example, participants helped restore the Frisian bird ringing stations in the Makkumer Súdwaard in the Dutch provence of Friesland. This year, part of the entry fee will be donated to research into otter habitat in the provence of North Holland.

Over the years, Rondje Pampus has grown into a well-known swimming event that attracts participants from all over the Netherlands and even from abroad. The event emphasizes the importance of nature conservation and sustainability, while at the same time celebrating the unique cultural and historical value of the area.


fish migration river

Every year, participants of Rondje Pampus swim for a good nature cause under the motto: You experience nature in open water! Last year, participants swam for the research into the habitat of the otter in Waterland. This year, a portion of the Rondje Pampus registration fee goes to a very special nature cause: the planting of native vegetation around the fish migration river.

The IJsselmeer area is the largest freshwater lake in Western Europe and is an important area for fish and birds. The construction of the Afsluitdijk abruptly interrupted migratory fish routes. Therefore, a fish migration river is being constructed at Kornwerderzand, cutting through the Afsluitdijk. Fish can use this river to migrate from the Wadden Sea to the IJsselmeer area and vice versa.

Allowing migratory fish to swim back and forth between the Wadden Sea and the IJsselmeer is not as simple as making a hole in the Afsluitdijk. Years of thinking went into determining the best design for all types of migratory fish. It is the first time in the world that an artificial tidal river is being constructed on the border of fresh and salt water. What’s remarkable is that not a single drop of salt water ends up in the IJsselmeer, so the lake remains a source of drinking water. The Fish Migration River thus offers a safe solution where gains for nature and the preservation of fresh water go hand in hand. The construction of the Fish Migration River is still in full swing. Around the river, gentle shallow shores will be created, where It Fryske Gea will grow plants and reeds, providing shelter for fish.


fortisland pampus

Rondje Pampus takes place on and around the unique Fort Island Pampus. Pampus (officially Fort aan het Pampus) is a fortress island in the part of the IJmeer that belongs to the municipality of Gooise Meren. The artificial island was built in 1887 as part of the Defence Line of Amsterdam to defend the channel Pampus against attacks from the Zuiderzee.

Sunk into the island is the massive Fort on Pampus. Once built to defend the entrance to Amsterdam through the IJ, it is now an abandoned ruin. The fort stands on 4,000 piles 11 meters long, and the buildings are a combination of concrete and masonry bricks. The fort has an oval shape and the main building has two floors.

The name Pampus is associated with 400 years of history. From impregnable shallows of the 17th century, where ships lay off Pampus, to figurehead of the 19th-century Defence Line of Amsterdam, to 21st-century UNESCO World Heritage Site! Learn more about the history of this special island on the Fort Island Pampus website.


The 12th edition of the Round Pampus took place on Saturday, July 29, 2023. Over 400 participants swam 1, 2, or 3 laps around Fort Island Pampus in the IJsselmeer. With this, these open water swimmers not only delivered a remarkable athletic performance but also contributed to the research by Landschap Noord-Holland into the living habitat of the otter in the vicinity of the Ilperveld.

This year, the Round Pampus 2024 open water swimming event will take place on Saturday, July 27, 2024. Participants can choose the distance they swim: 1, 2, or 3 laps around Fort Island Pampus. One lap is 900 meters. Entry tickets are available exclusively through our webshop. All participants will receive an email with detailed information about the swimming event.

A portion of the registration fee goes to a very special nature cause: the establishment of native vegetation around the fish migration river. Around the river, soft shallow banks will be created, where It Fryske Gea will allow plants and reeds to grow, so that fish can also find shelter here. The realization of this nature goal is made possible by the following partners and collaborating organizations of the Round Pampus Foundation:

If you want to stay informed about the latest news on Round Pampus, follow us on Facebook, Instagram, or Strava. More information about the terms and regulations can be found here (in Dutch). If you have a question about the Round Pampus swimming event, please use the contact form on our website.


Rondje Pampus Challenge

Can’t participate in the Rondje Pampus swimming event, but still want to participate in an alternative way? Sign up for the virtual Rondje Pampus Challenge for free!

Swim a distance of 900, 1800 or 2700 meters in open water or in a swimming pool during the weekend of the Rondje Pampus swimming event. Record this swimming activity with your watch or your mobile and share the result with us on Strava. Not only will you have a chance to win one of the ten tickets for the next edition of Rondje Pampus, but you will also help to draw attention to the vulnerable nature in the IJsselmeer area.

Signing up for the Rondje Pampus Challenge is easy. Visit the Strava Club page of Rondje Pampus. Once you are on the Strava Club page click on Join Club or Become a Member. That’s all, you’re signed up for the Challenge.



Do you have a question after visiting our website? We are happy to receive an e-mail. Fill out the form below, click Submit and we’ll get back to you. If you want to stay up to date with the latest developments around Rondje Pampus, follow us on social media.

Weesperzijde 142
1091ET Amsterdam
The Netherlands

Chamber of Commerce regnr: 85285528

Please enable JavaScript in your browser to complete this form.

Partners and collaborating organizations: