Open water swim coaching

Designed around your individual needs and swimming goals

Let us know what you need Our training programme

Swim Serpentine 1 mile swim

Londons 1 mile swim serpentine

Open water swim coaching with Mark Kleanthous

Mark Kleanthous has been open water swimming for over 45 years, after overcoming his fear of outdoor swimming early in his journey. He has completed more than 40 open-water events and over 550 triathlons, including 44 Iron-distance triathlons.

For the past 28 years, Mark has been coaching swimmers aged 12 to 82, helping people of all abilities swim more efficiently, straighter, faster for longer, with or without wetsuits.

Enquire about teaching sessions See my swim coaching reviews

Nervous beginners

Prone to anxiety or panic in open water or petrified of open water lakes, river, sea?

Mark will build your confidence, so you remain safe and calm. Mark has considerable experience, providing you with the tools to make you control your anxieties so you can enjoy your open water swimming.

Find out how we help

Pool swimmer to open water

Mark will have you swimming even faster in your neoprene!

We introduce you to safe, enjoyable open water swimming, Mark will transform your technique and breathing enabling you to swim comfortably, confidently and apply your cardio fitness to swim well.

Competition coaching

From pool to open water, from pool to open water triathlons all distances

As a competitive swimmer do you want to compete in a regional, national swimming event, open water swim competition or triathlon swim? Mark’s immense racing experience will teach you how to gain the edge.

Let us know how we can help

60 Minute 1-2-1 Open water coaching session

Each session is designed around your individual needs and swimming goals. Mark swims alongside you for instant advice and feedback, correction, support and guidance.

Mark can provide neoprene wetsuits and accessories for hire or purchase upon request. Wetsuit hire with all sizes of open water specific wetsuits for male and females and neoprene accessories hire: gloves, booties, and gear to provide comfortable swimming

Book your space

Personal coaching

Mark swims alongside you.

Instant feedback

Receive both spoken and visual feedback throughout your session

Written summary

Detailed summary highlighting key improvements and next steps

Bespoke training plan

Customised pool and open-water workouts

Dry-land exercises

Coaching Kids with Confidence

Your Time line for event day

Nutrition Advice

Mark’s immense racing experience will teach you to gain the edge.

Deep water starts
Seeding yourself
Drafting to save energy and swim faster
Sighting to swim in a straight line
Saving energy to swim around buoys with speed and efficiency
Recognising how to amend your technique against a current
How to swim into the sun
Navigate the correct route
Overcome the glare on the water to avoid going off course
Avoid bumping into other swimmers

Outstanding reviews from our clients

Excellent coaching provided by Mark.

Mark coached me through my Ironman^® training 15 years ago, and is now coaching my daughter’s Open Water swimming. Very knowledgeable and supportive coach for all levels of ability. I highly recommend Mark.

Leah H, February 2026.

Mark is an excellent coach.

My session with him was my first experience of open water swimming. Mark was incredibly supportive and friendly. He assessed my abilities and just in that one session he was able to improve my stroke, breathing and speed. I cannot recommend him as an open water swimming coach enough. I’m definitely not in Ironman^® triathlon shape, and almost certainly never will be, but if you want to try open water swimming or want to improve your performance give Mark a call.

Rob Bell, August 2025

Great coach

Had a few swimming lessons with Mark - been a great coach helping me getting comfortable in the open water and helping me understand triathlon situations transition fuelling.

David Barnett, September 2025

Would highly recommend

I met with Mark a few times to work on my open water swimming skills during my Ironman^® 70.3 Weymouth build up. He improved my breathing , technique and fitness. He gave me the confidence I needed and improved my ability. Would highly recommend him and all his experience in the triathlon world.

Tyler W, July 2025

I will never forget your confidence in me.

Thank you so much for our 1-2-1 open water swim coaching the session. You got me in the water which was amazing enough! I was really nervous but wasn't showing it. But you made me think and do so many other things that I didn't get time to think about the lurking fish down there. Because you didn't see them as any sort of issue, then I gained confidence from that and I began to think that too.

Anna, Northampton

Mark is a great inspiration

If you want the best trainer, Mark is your man. He helped my children aged 7 & 8 to swim in open water and gave them excellent transition and dietary advice too. He put us all at ease, focused on the children and worked with their strengths and improve their technique. He encouraged them and gave them the "can do it, will do it" mind-set. Mark is a great inspiration and very patient especially when you have a cheeky daughter.

PJ (40 & Mum of 2 kids)

Thanks Mark!

Thanks to you Mark I can now swim front crawl every time I now open water swim thanks to you. You put me at ease from the moment I met you showed me how to correctly put on my wetsuit get into the water learn to relax and swim effortlessly.

Martin Lewis (53)

Thanks for helping me overcome my fears

You were my last chance to overcome my fears I have seen several other swim coaches but still could not overcome my fear of open water. Thanks for helping me overcome my fears, I can happily report since our coaching sessions I have not had one panic attack. You don't know how grateful I am of you helping me achieve my ambition of competing in open water swimming events and triathlons without the fear I used to experience.

I will be forever indebted to your time and effort you gave me.

Every time I got into open water even with a wetsuit on i thought i was going to drown! That was until i had an open water swimming coaching session with Mark. Your professional but calm coaching showed me how to get into the water and relax my breathing, this has made all the difference. I actually went swimming in the sea holiday without a wetsuit for the first time EVER because of your help.

Alice Woodward (61)

Thank you so much

I never thought I would learn so much and improve so quickly in just 2 open water swimming sessions with you. I wish I had used you 2 years ago. I easily managed to complete my 1 mile open water swim and you will be proud to know my partner who was watching me from the bank said I even swam in a straight line! Thank you so much I will use the knowledge and technique you gave me for the rest of my events this season. I will not hesitate to refer others to you and be in touch again when I plan on swimming longer open water swimming events.

Adam Coates (33)

From novice swimmer and cyclist i am now an ironman thanks to Mark

I cannot recommend Mark (Ironmate) highly enough. He has been my absolute inspiration and support throughout my triathlon journey.

As someone new to swimming, Mark’s coaching at the Box End swimming sessions helped in building my confidence in the water.

Mark supported me through every single step of the journey, helping me successfully complete my first 70.3 in 2024 and then a full Ironman distance in 2025. I truly would not have been able to achieve my goals without his expert guidance and constant encouragement. If you are looking for a coach who is genuinely invested in your success, Mark is the best!

Raju Thota

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