How To: “How much do I need to swim for – x – open water distance?”

With the Northern hemisphere open water season getting underway, and temperatures in many locations edging around the magic number, (10C/50F) , open water related questions inevitably arise as each year brings new swimmers and more triathletes.

A common question is some variation of:

I want to swim 1.5k/3k/3k/10k, can I do it or what should I do to prepare?

There are different answers for this depending on many factors:

  1. What is your swimming experience?
  2. What is your current swim training?
  3. What is your open water experience?
  4. Wetsuit or not?
  5. Sea, river or lake?
  6. How long do you have to prepare?

I have covered many aspects of these questions, such as getting started, essential rules of cold water swimming, basic skills, swimming in different conditions, etc. (The How To category has more of these).

  • To swim any significant distance in open water the first requirement is regular swimming every week. This seems obvious but some people seem to think it isn’t. For almost any distance from 1k up, you should probably be swimming a minimum of three times a week. If your intended swim is over 5k, three times is probably not enough. Less swimming experience means that building up to regular swimming should be a longer transition as sudden increases will lead to a) injury and b) burnout.
  • The second most important requirement, and one of the biggest mistakes beginners  make, is to not get sufficient or even any open water experience before the actual event. Open water is De Facto not like a pool. Every day is different: Winds blow (or not), from different directions at different speeds in different weather conditions. Water conditions change dynamically, even during events. **You MUST get appropriate experience beforehand**. You must practice your skills, especially sighting and navigation, but also pack swimming, rough water, fear, contact with other swimmers.

* **A wetsuit is NOT A SAFETY AID**.

Many experienced open water swimmers feel very strongly that people substitute wetsuits for training and experience. A frightening video that was pointed out by Evan on of 2012’s Escape From Alcatraz. Watch it. Experienced open water swimmers view this video with genuine amazement at the ineptitude on display both of swimmers and safety crew and logically therefore of the organisation. This is a lumpy day by OW standards but certainly manageable for experienced swimmers. Even has also previously discussed the matter of wetsuits and safety in open water swimming and made the excellent point that while a wetsuit may confer some protection for INDIVIDUALS, in a GROUP of swimmers the use of wetsuits lessens overall safety because organisers use them as a safety crutch, so to speak. See also Phil’s comment on this point in the comment section below.  Swimming in rough water is something that requires practice.


Just because an event allows you to enter with your limited experience means nothing. Some just want your money. Events which have real qualifications requirement are not elitist. The organisers are experienced and aware of the dangers and attempting to reduce risk beforehand. As I’ve said before, safety decisions are best made outside the water. These are the *good events*. We all have to build up through various qualification levels to get into longer swims. This is the smart way to do it and organisers that understand this are to be trusted. Faking your qualification puts you and others in danger.

* You cannot safely swim 1k this week, 10k next week and do a 15k swim in the third week. Increases in training should be limited to an average of 5% per week. You shouldn’t go above this unless you have previous experience in ramping up swimming volume. That means if you swim 5,000 metres this week, in a month you will be swimming barely over 6,000 metres. You can prove me wrong, maybe, in the short-term, but in the long-term to do otherwise will lead to inevitable injury.


There is no simple answer. However…

Endurance swimmers and athletes have a few rules of thumb:

  • You can swim in a day what you swim in a week.

This is a reasonable guideline for medium to longer distances. I find it is most used from about 20k to 45k distances. If you are swimming these distances then you likely have your own opinion and may disagree with me. This is absolutely fine, since you know what you are doing and we all are different and I’m not trying to give an absolute rule. If you don’t have experience however, this is a reasonable rule.

This rule breaks down at the lower end. If want to swim 1k open water, you should be able to swim 1k in the pool without any difficulty and you should be swimming at least three times a week and more than 1,000 metres. If you struggle to swim 1k in the pool, you shouldn’t be swimming open water at all.

  • You can swim 4 times longer than your longest training swim FOR ONE-OFF EVENTS.

This is a very old rule. The last part means that doing this in the absence of regular training means injury is more likely. You may get through it on grit but you won’t do it regularly.

So, I haven’t given you a clear answer. That because there is no single formula.

Open water requires training, experience and a realistic approach (because it’s dangerous and anyone who tells you otherwise is wrong).

Here’s a very loose training guideline that should help you swim your events comfortably, assuming you also have the open water experience. All of these assume one day of swimming open water per week from spring to your event. This is a much larger subject and this is very brief thumbnail sketch.

Target event: 1k. Swim 2k at least three times a week.

Target event: 1.5k/1 mile. Swim 3k at least three times a week, or 2k four times a week.

Target event: 3k. Swim 4k at least three times a week, or 4k three times a week

Target event: 5k. Swim 4k at least four times a week. Swim 5k once per week.

Target event: 10k. Swim 5k at least three times a week, but swim at least 4 times a week. Weekly target of 15k minimum.

Target event: 15k. Swim minimum of 20k per week.

Target event: 25k. Swim minimum 25k per week. There’s more variation here. Some  experienced swimmers like to train less for marathon swims. I’m not one of them and my own experience and what I’ve seen of others means I believe strongly that in marathon swimming you have to be trained for when things go wrong.


34 thoughts on “How To: “How much do I need to swim for – x – open water distance?”

  1. I have no idea if this will work, as I am writing this comment about 8 years after your post was written. I have been trying to find information about training schedules for swimming and I cannot find good recommendations. I find your post the most helpful, and as a beginner in swimming (I mostly run/cycle/workout) I was wondering for what distance I should train within 14 weeks.

    This coming September I want to participate in the Monte Christo Challenge by Marseille and the options for distances are 1k, 2k, 2.5k, 4k, and 6k. What distance would you recommend that I would train for, keeping in mind that I have 14 weeks to train and start as a beginner.

    Thank you!


    • Hi Jameemah,

      Fourteen weeks is a good period of time. I don’t what your designation of “beginner” means, as it could be either that you are just learning to swim or that you can swim but haven’t done any swim training.

      If it is the first, and you are learning then 1 or 2k would be the most I’d recommend, because while you may learn some basics, they will take time to become habit and to develop experience and confidence.

      If you can already swim with a decent stroke, then I’d suggest the 4 or 6K are attainable. I’d suggest you need to be swimming at least 4 days a week for those, and one of those should be open water to develop your experience. If you can swim a couple of shorter distances of 2 & 2.5k beforehand with someone else, that will be beneficial. I hope this is helpful – Donal


    • Hi Myrna, Lots of time. I’d say normal weekly swimming, (at least three times, preferably a minium of 4 times a week), swim at least 2k per session. Then, maybe 3 months beforehand, put your sessions up to 3 k per time, and swim open water at least once a week and you should swim 2k continuous at least once beforehand. Enjoy.


  2. Thanks for this guideline. Very helpful in planning my preparation for a 3.8 k swim. I am not sure if an error krept in the line Target event: 3k. You mention “Swim 4k at least three times a week, or 4k three times a week.” The last part doesn’t add anything. Did you want to say, ‘…or 3k four times a week’, or what?
    Nice post anyway.


  3. Thanks so much for this post. i completed a sprint triathlon in May. i am a lifelong runner/cyclist but had to get a coach to improve swim technique. after 4x/week swim sessions and a lot of visualization, i ended up coming in 4th in the swim portion (750 meters) for women and was ecstatic. i had never really enjoyed swimming until i improved my technique. now i love it.
    i would really like to do an open water ocean swim (my tri was in a river). the event i want to do is 2.5 km (1.5miles) in mid october in the med. i am currently swimming 2000 meters in the pool about three times a week, on 2 other days focusing on running and weights. i am thinking that upping one of my swims to 3000 meters each week will allow me to swim the 2500 meters in open water. do you think this is feasible?

    Liked by 1 person

      • thanks so much for answering! after i posted, i looked at the date of the post and thought it would be dead. i dont know what i would do for information like this if not for the internet! my swim coach is excellent but i havent found many people knowledgeable about open water swims!!


  4. Very glad to read this post. I’m about 90 days post back surgery, training for a 15K swim in September, and finally have hit the 20K plus mark for the last 2 weeks, and will continue. One day of speed work intervals, one day “fast” longer intervals, one long swim on Sunday, the other days just getting distance with good form. lots of dry land to get my core back to normal, My main problem is getting good ocean experience. Our ocean right now is pretty rough so it’s been vetoed for me because of my back. Trying to substitute a bit with lake swims (loads of other swimmers) and endless pool sessions with the “current” turned up- right now expect that I’ll be able to start in some salt water in June or July… I fear I’m missing some sort of something. What would you add? subtract? Thanks.


      • Thanks for the reply. I am working up to 10K. after about 5 right now my low back starts to get mean, but…I’ve been assured as my core gets more normal again that my distance will improve….


  5. Very good post and great guidelines. I always like your posts (I’m a frequent closet reader) but this one was particularly useful as I like how you breakdown rules and training suggestions. On that topic, I have a question. Before 2011, my only OW experience was with wetsuit in San Francisco (swam Alcatraz 3 times). When I moved to London in 2011, I started non-wetsuit year round OW and it changed everything. It took me a while to get used to not having the same buoyancy, using my legs, improving my stroke, but I now wouldn’t swim other than “skins”. This year, I took part in a 5-man and 6-man English Channel relay (1st attempt, unsuccessful, 2nd attempt, successful). It was really fun and exhilarating. Swimming with so much ocean around me was quite unique (and scary at times). I swam respectively 3 and 2 legs (1 by night), in what I think are considered great conditions. I would now love to do a 15K next year (a lake with island hops along the way) but I’ve never swam that much. My current training regimen is 2 days/week pool (1 mile), 3 days/week OW (1K currently, temp around 8.5C). Am I mad?


    • Thanks. Congrats on your Channel relay.For a 15k OW swim yes, I’d say that is really insufficient training. You may finish (though I doubt it), but the goal is to enjoy it, not injure yourself doing so, and to my mind, not completely burn out afterwards.


      • Hi Donal, I realize I was quite unclear. I haven’t started training yet for next year’s swim. That’s why it looked insufficient to you and you were quite right. My current swim regimen is in “winter maintenance” mode but if I do put together the logistics for my goal (it’s in the initial planning stages), I’ll definitely follow your guidelines in the near future. Anyhow. I’ll keep reading your blog and I’ll learn from it. Have a great day.


  6. Pingback: Swimming for beginning open water swimmers and triathletes is like planting a tree. Twenty common beginner triathlete questions answered. | LoneSwimmer

  7. Hi, I’m a beginner triathlete and pretty good swimmer – I train in a pool but have also done open water. Although I’ve never swam long distance continuously, I train 2500-2800 meters though. I’m planning on doing a 3k swim in 3 weeks. Is it possible? Advisable? Thanks!


    • Hi Donna,

      If you are swimming that distance regularly, at least three times a week, then you should be fine. I’d suggest though dong a couple of longer swims in the pool, maybe 4k. Also do a few of your sets in the next two weeks as either 3 x 1k, or even a 2k or 3 k straight through. Have fun!


      • Thanks so much for your reply. I forgot to mention I’ve been doing this only on weekends. Will try to get some more swim days for the next few weeks though.

        Thanks again!



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  11. Phil, your comment about the Dart 10K is interesting. That was my first 10K. Prior to that I had done a couple 5Ks and other shorter swims. I had only one wetsuit, a farmer-John very thin on the the mils, and had no intention of buying a full suit.
    I didn’t have the resume then to swim the Dart naked, but I still had to fill out all the forms and got the white rubber band wrist band that naked swimmers got. And in the end, I wish I had pushed to just swim in my trunks. The rash/scars I got from the wetsuit stayed with me for over 6 months.


  12. “I wish that when they asked us: ‘What is surfing?’ I would have said it’s a spiritual activity, and no just a sport, because that’s what put us on the wrong track.” – Nat Young, 1966 World Surfing Champion

    Not sure why that came to mind I guess there is a lot of truth in what Nat said and why should it be any different for swimming? Money does win in most cases. All the more reason that people like you and blogs like this continue doing such a great job with the prolific amount of information that’s put out.

    Perhaps a good place to begin is for the open water swimming community to lead by example. It’s vital that the knowledge and skill found in places like this be passed on and transfered to the sea. That was the vision of George Freeth and for those of us who’s playground and passion is the ocean then so too it should be ours.


  13. Excellent Post Donal,

    I hadn’t heard about the Alcatraz Tragedy let alone the amount of swimmers pulled from the water. 10 degrees difference in temperature is huge and with open water already being a very complex system and between event organizers and swimmers clearly not knowing their stuff is it any wonder? If anything it proves that the whole system is already overloaded, accidents do not just happen there’s always a build up and a series of mistakes that can be avoided.

    It comes down to knowledge and training from both sides. I know people for example who on dry land are sensible enough in their decision making in that they would take very little risk. They also wouldn’t dream of swimming skin in cold water. However with a wetsuit they all of a sudden take on this kind of rambo attitude. Which is odd because they’re not like that in anything else. If wetsuits allow consciously or subconsciously or a little of both that rambo type to emerge then its a very dangerous thing. Personal responsibility is one thing but how can we be collectively responsible?


    • That’s a very good question Sam, and I honestly only think that a requirement of previous official swims is the only way e.g. want to swim Alcatraz in an event? You must have swum 2 miles in an actual event. But it’s easy for me to say that here in Ireland, when in the US triathlon is huge business (it is here too but with our small population at least there is some chance of dong that, and for many events this would reduce money and therefore revenue, & money wins in most cases.


  14. Great article. Really enjoy reading your blog. Would love to chat to you about making the transition to fully non wetsuit OW swimming. I’m swimming 2k per week one session in the wetsuit with the last 3 weeks. Was swimming most of last summer 3/4/5k without a wetsuit but as always I never managed to keep it going through the winter. Work, kids, weather, darkness … always something to break the regularity in sept/oct and suddenly it’s too cold. So here I am back in the wetsuit in early summer trying to figure out how soon I can ditch it and how I can plan to keep swimming through next winter!


    • Hey Meredith. If you lose your cold water hardening by stopping for months, then you have to start anew each season and acclimatization is a long process. That is the primary reason we swim year round. Swimming once a week, even missing an occasional week is enough to retain most of the gains. Then with those gains, each year the water reaches a comfortable temperature earlier for the skin swimmers than for the wetsuit folk. There is no easy solution I’m afraid. You can take cold showers regularly and wear less clothes in winter, and there’s no doubt that helps, but it’s still secondary to getting the water.


    • I know a good few people who wear wetsuits during the winter and always revert to skins for the summer. Most of them will stay in skins for as long as they can late in the year (usually to late October) and have a predetermined date for “shedding the suit” in the summer, 1 May and 1 June are common dates. Just pick a day and go for it! I’m doing regular 3 km swim non-wetsuit at the moment not having swum in the open water at all during the winter, so it can be done…

      Liked by 1 person

  15. “A wetsuit is NOT A SAFETY AID” – Tell that to event organisers!

    Don’t get me wrong, I have nothing against wetsuit swimmers so this is not a “us” vs. “them” comment but I have found it very strange that with a lot of events (For example The OSS Dart 10K, The Henley Bridge to Bridge 14K) if you wish to swim them non wetsuit you have to supply a swim resume and apply for special permission, i.e. actually prove you are capable of doing the swim. However any muppet who has purchased a badly fitting surf wetsuit from Tescos the day before can take part based purely on the requirement that they have turned up on the day with a wetsuit on. The other thing that is a worrying trend is some events are now charging extra for people to participate non wetsuit, claiming that the extra money is to pay for the additional safety cover that these swimmers supposedly require. :-/


    • I agree Phil. I also, contrary to assumptions in some quarters, have nothing against wetsuits. I started out winter swimming in one, we embrace wetsuit swimmers openly in Sandycove, there are in fact more of them than us. I like to think as wetsuits as a gateway drug in open water swimming. (Note to self, future post title).

      The same situation has arisen here, particularly because of triathlon’s temperature restrictions. Until event organisers embrace pre-swim qualifications are the most important safety step they can take, I don’t however see a ready resolution.


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