Dave Van Mouwerik - Lake Siljan

Hjortnäs to Mora

20.3 miles

11 hours, 39 minutes on July 26, 2013

Observed and documented by A. Hellgren and D. Van Mouwerik



Swim Parameters

Route Definition

Lengthwise (southeast to northwest) crossing of Lake Siljan, Dalarna County, Sweden: Hjortnäs to Mora.

Distance was defined by 8 waypoints to plot the route across this eccentrically shaped lake.

See this map to locate Lake Siljan within Sweden:

Historical Background

I had a Swedish friend check with the Mora Chamber of Commerce and a local radio station and newspaper, to see if anyone recollected a marathon swim taking place in Lake Siljan. He uncovered no stories about any historic swims, but no truely exhaustive search was performed to be able to learn if Lake Siljan had been crossed before by a marathon swimmer. I cannot claim that Lake Siljan has never been crossed before by a swimmer, although I am inclined to think that no such swim has previously occurred. (Furthermore, I have noticed that if Swedes aren’t wearing cross country skis for more than 3 hours, they get kind of jumpy, and thus marathon swimming would be especially challenging for them. This, then, is further evidence that the lake has never before been crossed by a swimmer…)

Swim Data

  • Start Time/Date: July 26, 2013 at 03:43 in the morning
  • Finish Time/Date: July 26, 2013 at 15:22 in the afternoon
  • Swim Duration: 11 hours and 39 minutes

Summary of Weather Observations

  • Air Temp: min 64.4F (18C); max is unknown, but expect approx. 84.2F (29C)
  • Water Temp: min 64.22F (17.9C); max 71.96F (22.2C)
  • Winds: Force 0-1 (calm to 3 MPH)
  • Skies: clear with some clouds; light rain in last 1 hour of swim

Support Personnel

  • Pilot: Stig Nielsen
  • Vessel: “Cornelia”, a 23 foot, 1968 Salto
  • Crew: Birger Hellgren
  • Paddlers: Ove Lissmors, Emil Lissmors
  • Observers: Anders Hellgren
  • Backup Vessel: a Rhyds 16 footer; Pilot Dan Hellenberg, Crew Agneta Andersson

Without this group of Swedes, I never would have been able to accomplish the planning and execution of this swim. I originally met Birger Hellgren and his wife MajLis and their two children in 1978. They live in a small town in central Sweden called Vansbro (about 40 miles from Lake Siljan). The support crew were all related to one another. The boat pilot, Stig, was Birger’s nephew; the paddlers were his son-in-law (Ove) and his grandson (Emil); the crew leader and main observer was Birger’s son (Anders). When I met Anders in 1978 he was about four years old, and it never occurred to me that thirty five years later he would play the central role in logistics, planning, navigating, and observing of my swim across Lake Siljan.

Rules and Conduct

  • Swim Category: Unassisted Marathon Swim
  • Swim Rules: Equivalent to standard MSF Rules for unassisted swims (though MSF Rules did not yet exist in 2013).
  • Standard Equipment: Swim goggles (Water Gear); Single latex cap; Speedo; Vaseline
  • Additional Equipment: None
  • Exceptions to Standard Rules: None
  • Feeding: Feedings every 45 minutes for first 3 hours, then every 30 minutes. Even feeds: Heed Perpetuem and 1 packet GU; Odd feeds: Heed Perpetuem and 2 Fig Newton cookies; Water when desired


The Vision

I spent about 18 months in Sweden and Norway in 1980 and 1981, working on various sheep and dairy farms. I have stayed in touch with many of the people I knew from this extended stay, and I decided to visit them, and to incorporate a marathon swim into my travel plans. The extended Swedish family that I knew lived in Vansbro (in Dalarna), and the sixth largest lake in Sweden is located about 40 miles from Vansbro. So this lake (Lake Siljan) was an obvious choice for my swim, both for logistic reasons and because it was large enough for my purposes. (I wanted to swim a route at least 20 miles long.)

In December of 2012 I determined that I would visit Sweden and do the Siljan swim in the late summer of 2013, so I put a slideshow video together to announce my plans to myself and to my friends. This was the vision:

Siljan vision from MSF on Vimeo.

The Route Defined

The intent was to develop a route that was an obvious crossing of Lake Siljan, and that was at least 20 miles long. The lake is very eccentrically shaped, but Anders and I were able to come up with a satisfying route that crossed the lake. We collaborated throughout the winter of 2013 using email, Skype, DropBox, and Google Earth.

When the ice melted in May, Anders took his boat up to Siljan, to try out some of the routes we’d developed using Google Earth. Based on the coordinates from Google Earth, he made a trial run of the route, using a Navibe GPS puck to identify his location on a laptop on board that was running software called Fugawi Global Navigator. This software was displaying a digital map of Lake Siljan, with the proposed way points overlaid, and with the boat location identified on the digital map on the laptop screen. The proposed way points were vetted and shifted when necessary during this trial run.

See this table of the eight waypoints, identifying both their coordinates and the specific distances between waypoints:

Overview map of the swim route:

Overview map of the swim route (the last 8,000 meters):

Siljan swim start (60 47 46.67 N, 14 57 27.60 E):

Siljan swim finish (61 00 24.06 N, 14 33 32.52 E):

Representation of the Siljan swim route in Google Earth: Download KMZ

(I am not sure why the Swim start and Swim finish are slightly mislocated within Google Earth. The swim start is located on the beach when represented with Anders’ GPS software, but in Google Earth the start is located 12 meters into the lake. Also, the swim finish is located at the edge of the beach when represented with Anders’ GPS software, but in Google Earth the finish is located 40 meters from the lake’s edge.)

Tides and Currents

  • Local tide predictions: Not applicable (this is a lake swim)
  • Surface current predictions or observations: There was some thinking by several people that regularly fished in Lake Siljan that there is a mild counterclockwise circulation in the main body of Lake Siljan. For this reason we designed the route so that when we passed through “Storsiljan” (that main core of the lake), we would be crossing it at its northern side, and taking advantage of any push that a theoretical counterclockwise current would provide:

The Evidence

Observer Log

See original log below. Note that the heading information of the swim log was not fully filled out by the observer, Anders Hellgren. I completed the form, and identified the fields I personally entered with brackets, thus for example “[TEXT]”:

Download PDF

See log transposed into a spreadsheet here.

GPS Track

The GPS unit on board the escort boat during the swim was used to track the boat’s location relative to the route defined by eight waypoints. The actual GPS positions during the swim were not recorded into a data file.

A SPOT device (the SPOT 2 Satellite GPS Messenger) was on board, and was used to display out the boat location during the swim to people interested in following along with the swim from my blog site.

The SPOT Server was not working for first half of swim (except for three sporadic points). My observer and crew chief (Anders Hellgren) had his laptop and GPS software on the boat, and had WIFI connection during the swim. He was looking at the SPOT device’s webpage, and realized that no points were being displayed.

Alarmed, he rebooted the device but still no points were showing. He remembered that my Swim Instruction Document had the name and phone number of Davis Best, who has been my crew leader in previous swims. You can see in Ander’s log entry at 4:46 am that he made a call to Davis to get advice on getting the SPOT device to work.

So imagine it, Anders makes a call to Davis at 4:46 am from a boat on Lake Siljan to Davis (where it was 7:46pm the previous day), to see if Davis can give any advice on getting the SPOT points to display. Davis called the SPOT support line and learned that the actual SPOT Server was down for an unknown period of time, and nothing could be done about this. He called Anders back, and let Anders know that there was a confirmed problem, but that it was beyond anyone’s control but SPOT. This was a great relief to Anders; he was happy that he had not been the cause of a problem with the SPOT device.

Anders mentioned to Davis that I was not aware of the problem with the SPOT device, and that he was not sure if he should tell me about it not working. And then Davis and Anders made an excellent decision. They conspired to NOT TELL ME about the problem with the SPOT device. Davis knows from experience that when I swim I want to hear unadorned true facts that are stated simply and accurately. And despite this, he knew, and he was absolutely right, that this information should be withheld from me, as it would “get into my head” and cause me needless grief and perplexity, about which I could do nothing. Thanks for that, Davis and Anders!

In an email, Anders recounts his version of the story:

I was very nervous that day. And when the spotdivice not work I didn’t now what to do. I was trying a lot of things. And then i been thinking of Davis and I beginn to search for his number then I called him and ask what to do. After a while he called back and told me the spotdivice was down for a moment. Then he ask me if I have told Dave about that problem and i said no, then he said do not told him about it. Because if I told him, he should be thinking to make a solution of the problem so that was no God for the swim. Haha.

About halfway through the swim, the SPOT server started working again, and so SPOT data was later available for download for the last half of the swim, plus three sporadic points from earlier in the swim.

See SPOT data here:

A review of the CSV data shows that the 1st track was at 18:50 on 7/25/2013, which, accounting for the 9 hour time difference between California (which the SPOT device was reporting the time for) and Sweden, correlates to our start time of 03:43 Swedish Time on 7/26/2013. And the 35th track (the first of 7 tracks that represent the end of the swim, when the escort boat was hovering at the boat dock at the finish) is time-stamped as 06:23 (SPOT device was reporting California time), which in Sweden was 15:23 on 7/26/2013). This corroborates well with the observer’s log which notes the swim as starting at 3:43 on the morning of 7/26/2013 and ending at 15:22 on the same day.

Swim Report

I wrote a series of 14 journal entries in The Siljan Diary, to chronicle the lead-up to the swim. Note also that the 14th (and final) journal entry is the Swim Report, and it includes several photographs of the swim. In some of the entries I tried to nibble at various aspects and emotions encountered in marathon swimming. Entry XIV included below:

I am at Anders’ house now, as he has a solid wifi connection. Birger and MajLis are “old school” so no wifi at their house. I’m struggling a bit with this keyboard, though, because it has located letters like “ö” and “ä” an d “å” in places that I expect other characters to be…. And forget about “@”, because you have to hold down 3 keys at a time to coax the “at” sign to come out.

As you maybe saw from earlier posts, the practice run on the Tuesday before the swim was troubling: strong wind, and water temps down to mid 57 degrees F. The weather report that day had called for 1 meter-second winds (2.2 MPH), yet we had 8 m/s. Had I swum on Tuesday I am pretty sure the swim would have failed.

But Thursday night, just before the Friday swim, the weather report was saying the wind would be between 0 and 1 m/s all throughout the swim. The support crew was very optimistic about the Friday situation; I tried to point out that……uhhhhhhhh…..guys….. the weather report on Tuesday had it way wrong, so how can we be overjoyed that the same weather report is calling for little to no winds on Friday? How can we believe it? They were not in the least distressed by this combination of logic and pessimism, and so I eventually I quit trying to make this point.

(However all throughout the swim, until I was about two or so miles from the finish, I was keenly aware that the proverbial shit could hit the fan in the form of wind picking up and causing a lot of trouble. And if it did, it would (like Thor’s hammer) smite us every one, but especially the swimmer and the kayakers. I guess I am still scarred by the last few hours of my Tahoe swim, which was in some way like my own private Vietnam……)

Anyway we rolled through the 7 legs of the swim. I knew them well in my head–Anders and Stig and I had worked them out over the winter, and put together they represented 32,700 meters from start to finish. The first leg was 7,500 meters long, and that was basically just a settling-in for what would be a full day of swimming. The tough leg was the second one–it was 17,000 meters long–basically just over half of the swim. I knew that if/when i finished that leg I would have broken the back of Siljan, and that the likelihood of finishing the whole swim would be very high. (Although even after that leg, I fretted about the possibility of wind coming up.)

At one of the feedings along this leg, I made a plan with Anders to have a cup of coffee and five ibuprofen at the first feeding following the finish of this leg. So that gave me something to look forward to, and indeed when I’d finished that leg I drank the coffee while treading water, feeling ever more certain that this swim was in the bag.

The third leg was 6,500 meters long, and this was the leg that pointed me just to the left of a large saw mill. It seemed like the sawmill was perched on a vanishing horizon, and it felt like an endless amount of time for us to approach the saw mill–I was aching for it to be in my rear view mirror!!. During this part of the swim I became quite crabby, and I decided that possibly “we” (namely Anders and Stig) were not navigating correctly. I questioned Anders about this very directly a couple of times, and he assured me that the boat was on track, and he said to me “Dave you just have to trust me that we are going the right direction”. I was like an overwrought cat that had climbed up some curtains and was hanging up high near the ceiling, and Anders was the voice of reason and confidence that talked me back down from this place. All through out the planning stages of the swim I developed great confidence in, and reliance on, Anders. And during the swim, he was a rock solid leader.

Marathon swimmers will sometimes trade stories about things they have seen while levitating above those deep and unconcious waters for long periods of time. Especially, I think, if it is night time and the swim is in the ocean. On this swim I was happy to have three odd experiences. They weren’t hallucinations, but they were feelings or visions born out of shrinking your head down into a tunnel so that you can focus just on your swimming and let everything else in your life fall away from you….and you grow hypnotized by the steady 60+ strokes per minute, the regular breathing, hour after hour…….

It happens that I had a cousin, named Jim, who died in Sweden ever-so-long ago, when he was studying in Uppsalla, when he was about 22 years old. In preparing for this swim, I imagined that maybe, since this was where Jim drew his last breaths, that there would be a possibility, in some way, of encountering an extra strong memory of him, and that possibily it could happen while I was swimming in Lake Siljan. Alas….this was not meant to be.

But….between about the 6th and the 10th hours of the swim, I did have some cool things happen.

1) I was swimming along, and suddenly a large white snake, maybe 3 inches thick, swam directly in front of me from left to right. I recoiled in panic, and gradually realized that the sun from behind me had refracted off of a couple of scratches on my left swim goggle, and had provided an illusion of a snake swimming directly in front of me. But the idea is that the long hours of swimming put your mind in a creative and suggestive and open state of mind, where the line between reflected light and thick white snakes can blur…

2) I have swum in the ocean many times when sea lions approach and swim nearby. It is easy for me to recall their natural swimming motion as they move through the water. At one point in Siljan I sensed that a sea lion swam close to me, approached the surface, and then pushed up a rolling bump to the surface of the water, before diving deeply and disappearing. (The Swedes assure me that no sea lions live in Siljan….)

3) I breathe to the right and to the left, and then occasionally I lift my head forward so that I can become situationally aware of boats, kayakers, landmarks along the shore etc. One time when I looked up, I saw a splash on the water in front of me, and briefly I was certain that sitting atop the water was a white origami bird, just a few yards in front of me. So, although I was not treated to a strong encounter with my cousin, I did at least get to feel a blurring between the explainable and the not-really-explainable world.

The fourth leg was 700 meters in length, and it set us up for the zigzag entrance, between red and green buoys, into Saksviken. The final 3 legs were only 300 meters each. The swim was in the bag. In the final 300 meters, three people jumped in from a point of land and swam near me. As it turned out, it was 3 of my Norwegian friends–Tor-Erik Risberg, Nils Hagen, and Kristian Hagen-Risberg. So it was a fine swim. I had started swimming at 3:43 am on Friday morning, with enough natural light that there was no need for flashlights or glow sticks. I completed the swim 11 hours and 39 minutes later, at 15:22 in the afternoon.

The swim was 32,700 meters long (20.3 miles). The boat escort and kayakers and observer and crew leader performed very well. Our more-that-six-months of preparation paid off. My training paid off. Lake Siljan provided us a window of time during which we could slip through her, from the foreleg of the cat to the tail of the fish. My nephew Jesse captured the moment in spirit in this final picture of the chimera. Below his drawing, be sure to look at the gallery of photos from the swim.


Lake Siljan: It looks like a cat with a fish chomping on its back:

It really does:

Support crew training:

An hour into the swim:

Several hours into the swim:

Swim’s end:

Mission complete:

Newspaper Articles

Mora Tidning, July 26, 2013: Pre-swim article:

Link to article

Mora Tidning, July 29, 2013: Post-swim article:

Link to article

Translation of articles to English