Ailen Lascano Micaz - Rio Negro (Primera Angostura to Viedma)

Primera Angostura to Viedma

107.5 km (66.8 miles)

17 hours, 24 minutes on 6-7 March 2021

Observed and documented by Leomarys Ñañe



  • Name: Ailen Lascano Micaz
  • Gender: female
  • Age on swim date: 30
  • Nationality: Argentina
  • Resides: Viedma, Rio Negro, Argentina

Support Personnel

  • Boat 1: Juan Lascano (pilot) & Sebastian Perez (copilot)
  • Kayak: Nelly Micaz (kayaker)
  • Boat 2: Gabriel Hernandez (pilot)
    • Luca Lascano (Feeder)
    • Mariano Sivori (Doctor/Observer)
    • Leomarys Ñañe (Observer/Documenter)
  • Land Support
    • Chingolo Andrade
    • Gustavo Castro
    • Flia Michelena
    • Fernando Cadenasso

Swim Parameters

Route Definition


The only similar preceding experience was an assisted swim performed by Sebastián Rodríguez in March 2019. He also arrived at Viedma but his start line was a few kilometers down the river.

Swim Data

  • Start: 6 March 2021, 22:28 (America/Buenos_Aires, UTC-3).
  • Finish: 7 March 2021, 15:52
  • Elapsed: 17 hours, 24 minutes, 5 seconds.

Summary of Conditions

Feature Min Max
Water Temp (C) 18 20
Air Temp (C) 18 25
Wind (kph) 8 15

GPS Track

Trackpoint frequency: 5 minutes. Download raw data (CSV).

Click to expand map.

Speed Plot

Feeding Plan

  • BOTTLE 1 750ml water and 2 spoon of maltodextrin
  • BOTTLE 2 750ml water and 3 gel with caffeine
  • BOTTLE 3 750ml water and 3 gel without caffeine
  • Carbo gummy as a replacement for bottle 3 in the end.

Observer Log

Download PDF


by Ailen Lascano Micaz


From 22.28 on Saturday March, 6th to 15:52 on Sunday March 7th, Ailén Lascano Micaz completed a non-stop solo swim in the waters of the Río Negro river connecting location Primera Angostura (Balsa Guardia Mitre) with the city of Viedma in Argentina. The (minimum) route distance was 107,5 km and the total GPS track distance was 114,67 km.

Per the Rules of Marathon Swimming for unassisted solo swims, Ailen completed the swim under her own power, without making supportive contact with any person, boat, or other object, and without assistance from any nonstandard swimwear or equipment.

Water temperature ranged from 18 to 20°C and the river’s maximum speed was 4 km/h, while some areas had backwater or countercurrent .

Ailén was escorted by 7 person divided in two motor boats (one manned with Juan Lascano and Sebastián Pérez, the other with Luca Lascano, Mariano Savioli, Leomarys Ñañe and Gabriel Hernández) and a kayak in charge of Nelly Micaz.


The only similar preceding experience was performed by Sebastián Rodríguez, who in March 2019 swam 109 km in 16:30 hours. He also arrived to Viedma but his start line was a few kilometres down the river compared to Ailén’s one. Sebastián didn’t swim non-stop and used a wetsuit in parts of his route.

In the city of Viedma there are summer open water competition “Cross the river”(cruce del rio), “Bridge to Bridge (Puente a puente) and San Andres-Viedma (15km). For some years there was also a Fina marathon swim 10km Patagones-Viedma .

Swimmer Statement

What inspired you to do this swim?

“I want to swim around the whole world, let’s start from home”

I’ve been swimming since I was a baby and for the last three years I’ve been involved specifically in winter swimming, participating in the events organized by the International Winter Swimming Association (IWSA) and the International Ice Swimming Association (IISA).

2020 was a challenging year, it was hard to keep on training and attending international competitions didn’t seem possible so I had to find a way to motivate myself, to set new personal goals.

I started dreaming of this challenge after most of the ice/ winter swimming competitions were cancelled due to Covid-19. I needed something that kept me focused on, I needed a new objective. Around the end of August when the winter local personal challenges that I had proposed were finished (swimming in temperatures between 6 and 12º), I began to think about what the next goal was. If in the worst case, given the restrictions, I could not leave the city, what could I do in my river? In my list of "someday" swims I had written down these 100km from GM to Viedma, since it had been done in 2019 by Sebastian Rodriguez. I had it in my head but due to the icy competitions I had displaced it. Now was the possibility, however the decision was not easy.

I found myself thinking “What am I doing? Why am I planning a more-than-100km swim if I usually race distances from 25 to 1000 m top? (or the Ice Mile too)”.

The answer was clear: I wanted to get out of my comfort zone (again), I wanted to grow as an athlete, as a human being. I knew it was going to be different and hard, but not impossible. I always like swimming in open water, swimming in the different, changeable and winter swimming is challenging. Someone said to me that I literally and figurative like to break the ice and completely get out of the comfort zone.

In addition to being inspired by the challenge of facing the different and difficult, when I was organizing the challenge I was realizing the importance of other aspects and these other two especially mobilized me ... to make this sport visible and make visible the role of women.

Swimming is essential, we have access to the sea, rivers and lakes, because here in Argentina we have everything and still many people do not know how to swim, many people do not feel safe.

On the other hand, doing it without a suit and according to the rules, doing a continuous swim without assistance was a way of approaching international challenges and giving people the opportunity to know that it is possible. Here we have a beautiful river for swimming, where you can do beautiful swims. We have incredible water mirrors in the country without pollution, without traffic, there are so many options and opportunities to swim, I feel that we have to communicate, enjoy and motivate more. I can show the places we have here inside. I can start from home. Since I was very young, I have swam in this river that is in my city, different distances, always training and/or enjoying. I know him and I love swimming here. It was a great opportunity to put my town, my river and my country on the map. I’ve already represented my country abroad, but Argentina has so much potential for open water swimming that I feel the world needs to know about.

Also within the framework of International Women's Day and being the first to achieve more than 100kms in Argentina, in the absence of records I was motivated to show the strength of women and their perseverance. There are many swimmers both in the pool and in open water that are doing amazing swims in Argentina and in the world, but I think that the role of women still needs to be made even more visible. I was inspired by so many women's swims to see that it was possible to make this happen that being able to do my bit made me happy. So many great swim I saw the last years. Champlian lake and 4 crossings to the English channel by Sarah Thomas, 4 laps to Manhattan by Jaimie Monahan, the Beagle and the Chungara by Barbara Hernandez, and so many more swim. So many incredible, intrepid, brave, amazing women inspires me every day. short words..

The opportunity to achieve this personal challenge, to do it without a suit, without assistance, in pursuit of the spirit of the original open water swimming. Create a local record and a precedent, to start new swims and new challenges. Making the sport, the role of women and the place visible, all this was an inspiration engine.

Please describe how you planned for the swim.

In September 2020 the preparation began, which meant a radical change in the routine that had to date, since it was the first time that I would do such a long journey. In icy waters the dynamics is different (when facing temperatures below 5 degrees) the distances are much shorter.

And while I love swimming, I prefer to do it in open water. Understanding that I was going to swim so much in a pool, in fish tank mode it worried me. I really like open water because I have that feeling of freedom, the water is always different. In the pool there is only the wall and you. So the hardest part of all was at that moment in September when I had to make the decision. The most difficult thing was to dare to say yes, to go through all the doubts, all the fears, make the decision and believe 100 percent in it. Once I took it everything after was flowing.

My coach was there.My family supported me in everything, and they began to organize the logistics. Both my mom and dad knew the whole part of the river perfectly because they had done it many times in kayak. In competitions and recreationally. (we`re a sports family)

That was the most complex thing, having a water expert to direct the tour.

Then we continued to get the boats and plan the logistics of the land part so that all the security aspects were covered. A team was created and established. We asked a doctor to go in the boat and an international media reporter to record the swim.

My father was in charge of the logistics, he traveled the route several times more, created a map with the points of the river to take into account for its curves and risky parts (trees in the river) and divided the challenge into land points for supporting logistics on land.

On the other hand I am fully dedicated to the training and to learn and practice how to do the hydratation and how it was for my body. I trained in the pool every week day (no weekend because corona restriction), gym 3 times a week. Open water also three times, one longer on saturday. And close to the challenge I started the mental preparation with my friend Barbara Hernandez, who is a psychologist and helped me with mental tools for the swim.

Throughout the swim it had to start at night so the logistics had to ensure light. My father got all the elements to have good lighting and I looked for lights to put on my swimsuit and a neon yellow hat.

The original date of the swim was postponed from February to March and placed next to Women's Day. Everything was lining up.

The exact time of the swim was defined according to the currents. Because the Negro River ends in the sea, so the influence of the tides, being 30 km away, changes the tide every 6 hours and influences the River as well. The options were around 10.0 at night or at 5 in the morning. The conditions were better at night.

"Alone we can do so little; together we can do so much." – Helen Keller

For the training planning, I created a multidisciplinary team that provided support at all times, Daniel Tomaselli (coach) Luca Lascano (physical trainer), Nicolas Baglieto and Camila Alzerreca (nutritionist), Magdalena Kuen (kinesiologist), Barbara Hernandez (coaching) and Carolina Rodriguez (counseling )

And the team formed for the swim was the following:

boat to go well ahead watching the risks of the river at night: Juan Lascano (father-pilot) and Sebastian Perez (Boyfriend-copilot)

Kayak: Nelly Micaz (Mama)

Boat behind with hydration, doctor and documenter:

Luca Lascano (Brother-hydration)

Mariano Sivoli (Doctor-Observer)

Leomarys Ñañe (Observer-Documenter)

Gabriel Hernandez (Helmsman)

By land:

Chingolo Andrade,Gustavo Castro,Michelena family and Fernando Cadenasso.

How did the swim go, generally? Did you face any unanticipated challenges?

The swim had all the seasonings, starting at night, in complete darkness it was to be with the river that looked like the sky, the sky that looked like the river, swimming in the dark, not seeing my strokes. When I swam I got comfortable, but every time I braked to hydrate myself kind of made me dizzy. The last few hours I thought a lot about the sun coming up.

I was very well accompanied so that was very good, because it gave me a lot of peace of mind. The boat that guided the way had lights that I used as a reference, they communicated with handy and radio with the boat that was behind me and the kayak attentive to the side towards the corrections according to the curvatures of the river, the currents and the possible risks of trees in the river.

When the sun finally rose, the temperature dropped and the sun hid in the clouds all day. So much that I expected it I never really saw it! But I continued well, I felt comfortable. The hydrations left my belly warm and the crew always gave me words of motivation. Even though i didn't talk at all. In the first feeds I did, but halfway i started to need more concentration, so i didn't talk just in some exceptions.

The kayak next to me was key to following the path of the river well, which had many curves and areas of countercurrent or dead wate

with every hydration I was counting down and crossing out the places we passed that gave me guidance on where we were. But Approximately from 11 am I stopped thinking about how close I was or how much was left. Because I had the point San Javier as a reference, but about 5 km before the area begins my team told me but I understood that it was the beach, understanding later two hydrations after we had not yet passed the beach made me mentally complicated. Then from there I just concentrated on continuing to swim and searched my mind for words of encouragement, that my head was motivating and supporting me, reminding me why I was doing it, with whom I was doing it and who was waiting for me. I was thinking of swimming to the next hydration and that it was going to warm my belly.

At this time I think the discomfort in the shoulders also began. Although also in the hip and waist. Well the truth is that often something different started bothering me, thumbs, knee, forearms. They were like pains but I think that discomfort suits them better, because they were not serious. The sensations in the shoulders also bothered but not at the injury level, it was more a feeling of fatigue and exhaustion. Discomfort.

More or less the last three hours became more complex but at no time did I think of giving up. I had left a lot of things and trained a lot, I had a whole team and a community that was waiting for the swim. I felt like I hadn't given everything yet. I only had one thought and it was to swim until the next hydration, so on.

In the last hours the hydration had changed adding solid to the liquid part, I was interspersing with cereal bars and bananas. I did not want to eat, it seemed uncomfortable, slow. I chewed away from the boat, to stay well concentrated. I did not want to eat but felt it was necessary.

800 meters before arrival I had to go under the bridge that connects the city of Viedma with Carmen de Patagones, two different provinces. You cross the bridge when you come on a trip from places like Buenos Aires, and the feeling when you do it is to feel at home.

Seeing the bridge was exciting and invigorating. I felt the energy return to my body, the cold and the discomfort in my shoulders went away. I got really excited, picked up the pace and got home.

I came out of the water and I felt great. It has been difficult for me to get out of the water in other races much shorter. I was happy wanting to cry but I couldn't. I think I was so tired that I couldn't cry. We quickly took some photos and they took me home. I was very excited, I couldn't sit down. They gave me a blanket, a protein bar, a moisturizer and made me sit up and calm down. everyone was super tired. Within minutes everything started to go down and I got sleepy. I went to bathe quickly I ate two cereal bars and gatorade. It was 18 in the afternoon and I was already sleeping. I woke up at 4 in the morning, hungry. My shoulders were bothering me but overall I felt perfect. Eager to start the day. I stretched, I ate some cereal bars that I had close, drank a lot of water and returned to bed. At seven o'clock I got sleepy again and rested. On Monday I lived it with a lot of energy. I felt so good, the feeling seemed super strange, because I had felt worse, more exhausted in weeks of training load. Another strange thing wasn't being hungry, every meal I didn't want to eat much. but sometimes wanted to eat suddenly chocolate or felt my stomach empty.

Well finally the fatigue and lack of energy appeared on Tuesday, and more on Wednesday. The doctor and coaches advise me to stay calm and stressless all week. I did it. I understand recovery is an important part of the swim, physically and mentally. and i have more dreams, more goals, more swims to make real.


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