It’s on: Yster SUP’s Per Vallbo gives the inside scoop from SUP 11 Islands Challenge

Founder-led stories carry a unique weight in any sport – especially when those founders step onto the start line themselves. When leaders test their own equipment in some of the toughest conditions in the world, it shows a level of commitment that goes far beyond product design.

That’s exactly the case with Yster SUP, the premium Swedish brand, based in Malmö, known for its ultra-endurance and expedition-ready boards.

Yster has an ongoing relationship with the SUP 11-City Tour – from backing the event to Per Vallbo himself paddling the full 220 km / 130 miles last year, proving the durability, purpose, and philosophy behind the boards he designs.

Now, he’s closing out the year in style by taking on its sister event, the SUP 11 x (SUP 11 Islands) Challenge in Koh Chang, Thailand, running between 2 – 8 December 2025. We caught up with Per on Day 2 of the expedition while he was actively crossing the islands. This story couldn’t be any hotter off the press!

Hi Per, welcome back to TotalSUP. You’ve already completed the SUP 11-City Tour and now you are taking on the SUP11 Islands in Thailand? What were your expectations?

I have been looking forward to the SUP11 Islands in Thailand. I expected paddling in heat and high humidity, and that proved absolutely true. The heat and humidity are, of course, a major part of the experience, but that is exactly what makes the event such an exciting challenge.

I was eager to test myself in those conditions, but just as much to the atmosphere surrounding it. It is a brilliant opportunity to enjoy the sport and to meet both old friends from previous races and new ones along the way.

Photo by Edwin Westra

The SUP11 Islands is known for its tropical heat and open-ocean conditions. How do you prepare for these conditions?

Well, it is difficult to prepare for tropical heat when you live in dark, wet and cold Malmö in Sweden. Since I was not sure what the conditions would be like, I have focused my training to long-distance intervals, around 10-20km in rough water. From experience, I know that three areas of my body are particularly vulnerable to fatigue: the legs, the hands and the lower back.

Photo by Edwin Westra

So, in addition to time on the water, I run regularly to build general resilience and, in particular, the ability to endure static load over longer periods of time. The hands’ skin is a particular concern. Prolonged contact with salt water already causes wear, and adding heat and sun cream makes it even more challenging. I have found that the only effective approach is to build genuinely thick, durable skin on my hands through consistent time on the paddle. Gloves do not work.

Now, a couple of days into the race how would you describe the conditions out there

The conditions were exactly what you would expect in this part of the world: hot and humid – like being wrapped in cotton. Although it’s really warm on the water, the good thing is that whenever you start feeling the heat, you can always take a quick plunge. Since it’s not a race by definition, the faster paddlers are actually encouraged to take a mandatory swim now and then to let the rest of the group catch up. Typically, the quicker paddlers also start about 30 minutes after everyone else.

The heat builds up quickly, but before long a cooling breeze arrives. The scenery is stunning, and we even spotted monkeys and huge fish – no sharks. My 3-litre  hydration pack lasted until the mid-day break, where I could refill.

I know many people are curious about the conditions on the SUP 11 Islands. So far, we’ve paddled in glassy water, upwind, downwind, cross-chop, and messy surfaces. Experience in ocean conditions is definitely recommended for this tour. What I didn’t expect was the current working against us along the shoreline at one point. It created some chop, but nothing too serious.

You’ve not only completed endurance races like the SUP 11-City Tour but also lead SUP Driven’s (powered by Yster gear) multi-day SUP expeditions in Sweden, where paddlers get to experience the beauty and challenge of long-distance touring in Nordic conditions. What advice would you give to paddlers who dream of taking on their first multi-day SUP challenge – whether it’s an expedition in the Swedish archipelago or an event like the SUP11 Islands in Thailand? How should they prepare physically and mentally, and what are some of the most common mistakes first-timers should try to avoid?

That is a great question. Being on the water for multiple days, whether touring or racing, will put a strain on your body and engage muscles that you do not normally use as much. The legs and lower back, in particular, take a real beating, along with the shoulders and core, which have to work constantly to keep balance and propulsion. Often your legs are overlooked because you typically don’t think they would work that much but, imagine if you were to stand on a balance board for hours and hours over multiple days, then you realise that all micro-balancing really gets you after a while and eventually your legs will go spaghetti. That’s why it is important to get your legs in shape.

It is important to prepare both physically and mentally by building endurance, strengthening these key muscle groups, and practicing long sessions on the water so your body can adapt to the continuous load. A common first-timer mistake to multi-day expeditions is to believe that you can go down on your knees if you get tired. That is true to an extent, but you can only paddle on your knees for twenty to thirty minutes before your legs start to go numb, because sitting on your knees restricts blood circulation. This applies equally to multi-day SUP expeditions and endurance races. Adding to that, most SUP races do allow knee standing paddling.

Also, remember to stay hydrated and fill up your energy level throughout the day. And recover and prepare for the next day: drink a lot, eat a lot and sleep a lot.

What Yster board are you using for the SUP11 Islands – and why did you choose that particular model?

I chose my favourite inflatable board, the unlimited Yster ISUP 17’3” x 26” Linear – also known as the Yukon board. It was the first ISUP ever to complete the Yukon 1000, an extraordinary achievement by Janneke Smit and Ella Oesterholt of Team Yukon1000 SUPVenture Ladies  in 2022.

The following year, Craig Sawyer and Skip Innes of TeamSHACYukon1000 completed the same race on the same model and won the SUP category outright.

Photo by Edwin Westra

Obviously, the races cannot be compared in any terms of distance, conditions, load, or temperature, but the board’s pedigree speaks for itself. I wanted an inflatable board with excellent glide in flat water that also could handle rough ocean conditions and this one fitted perfectly.

For this race, I fitted a Yster SUP 7″ Shooting Rake Fin for maximum glide. I also wanted a fin that would not catch seaweed. That turned out to be a good choice because there were some floating seaweeds and also some tree leaves close to shore.

I am really impressed by the SUP 11 Islands concept – paddling between “11 islands” with lovely paddling conditions, great food, relaxed atmosphere and a great crowd of committed paddlers.

Photo by Edwin Westra

Thank you so much Per for this insider scoop and have an epic ride!

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Find out more about SUP11 x and follow the challenge on Facebook and Instagram.