The Ultimate UltraSwim Experience Awaits

Big marathon swim challenges like the English Channel can be very difficult to organise, often with long waiting lists or expensive solo organisation costs. Whether your aspiration is to take on the iconic Channel swim in the future, or you relish the idea of an ultra-marathon challenge, UltraSwim 33.3 now has two big swim options added to its next Epic Adventure Swim Race in beautiful Croatia in May 2025, including a 33.3km single swim between the two stunning ancient 12th century villages of Stari Grad, and Hvar Town.

If already the 33.3km over 4 days seems plenty (quite normal!), then the rest of this blog is maybe not for you - but why not get that 'end of winter' (if you're a northern hemisphere person!) challenge of UltraSwim 33.3 #7Croatia booked and have a goal to aim for over the next 6 months!

Entries to the ULTIMATE are strictly limited and there a significant financial incentive for the first 5 swimmers to confirm their entry in either the full ULTIMATE 33.3 or the shorter but nonetheless challenging 22.2km version, ULTIMATE 22.2.

Swimmers must be entered into the full UltraSwim 33.3 event, but will swap one of the event day swims for a full 33.3 (or 22.2km). The swims will take place between sunrise and sunset, with a minimum pace of 2.3km/h (or 2km/h) required.

A full additional support packaged will be provided, including a dedicated boat and skipper, live tracking, medical cover and a super course as part of the ULTIMATE Entry Fee supplement. You will be asked to bring your own support crew of at least one experienced person who will manage your nutrition feeds and overall well-being alongside our team.

In addition to your chosen UltraSwim 33.3 package, we will provide:

Planning, weather, set course, overall delivery

A dedicated co-ordinator and race director for the ULTIMATE
4-6metre support boat with skipper/observer, fuel included
Live tracking
Timing and results
MSF documented event ratification request where applicable
Medical cover on standby
Precision Fuel & Hydration product for the swim
Specific preparation webinar for ULTIMATE entries
On-site preparation session with Andy Donaldson
Specific pre-event briefing
Photo and video summary of event
Transfers to/from start and finish from/to hotel by boat and/or land
Training for boat skippers, radios, trackers (in addition to swimmer)
Additional safety equipment onboard each support boat
Remote monitoring of tracking throughout
Start and Finish lines
Dedicated WhatsApp channel for swimmers and support team
ULTIMATE specific Finisher medal

What you will need to provide

One support person who has some experience of supporting you or another marathon swimmer on a 5 hour + swim - in particular who has the knowledge to manage your regular feeding routine. A second person may also be on the support boat. Accommodation for at least one person must be taken through us at the event hotel(s)

Any extra specific nutrition, fresh food, and feeding equipment (eg feedstick if under MSF rules).
A medical certificate certifying fitness for the ULTIMATE swim
Your mental strength and desire to finish!

Potential courses for the 33.3 and 22.2

Q&A on #7Croatia ULTIMATE 33.3

What day of the event will the ULTIMATE swim be? Normally at #7Croatia it will be the second or third day, allowing you to use the previous UltraSwim 33.3 legs as warmup swims and the fourth day to enjoy the super finish in Hvar Town with everyone.

What happens if the weather is bad, is there a risk like many other long distance challenges that I don't get to swim at all? This risk exists but is very low compared with those other challenges, as we have all 4 event days to be able to achieve this swim, and have the resources in place to be able to be flexible.

How experienced does my support person need to be? They will need to be practiced and comfortable managing your nutrition and feeding regime (generally swimmers are feeding every 30 minutes on such swims, we can provide more advice on this of course), and equally have some experience on how to maintain both safe distance and correct protection for the swimmer to ensure the skipper acts as you require him to. Its possible we could provide someone - but at an additional cost - if you don't have this support person yourself.

How fast do I need to swim? With almost mid-summer daylight hours (0530-2015), the minimum average pace required will be 2.3km/h for the 33.3 and 2km/h for the 22.2 - if you cannot hold this pace, you will need to exit the water when asked. Allowance will be made for adverse current and conditions, with start / finish times adjusted accordingly - but there will be no swimming outside of daylight hours.

Can I just come for the ULTIMATE and not enter the overall event? No, unfortunately this is not an option due to the fact that we have to make commitments to 4 nights with our hotel partners and we must use the full package for every swimmer, and equally can’t block those rooms for just a part of the period. This may change at other venues in 2026 (currently this is the only venue we plan the ULTIMATE in 2025), but this is a constraint at #7Croatia that we can’t change.

Can I bring more than one person with me? Yes the boat that will be dedicated to you will have the space for 2 or 3 support crew, we just ask that at least one of the support team takes our partner hotel and transfer package (at the same level as you)

How late can I leave it to book? Places are strictly limited (by the ability to source appropriate support boats and skippers primarily) so you are advised to block your place immediately, pay your event deposit, and send us your marathon swimming resumé on epicswims@ultraswim333.com for our Race Director to consider - we cannot guarantee acceptance of all applications.

How much does it cost in addition to the UltraSwim 33.3 normal entry? 1500 Euros is the additional fee for the ULTIMATE 22.2 and 33.3, but the first 5 entries out of an initial maximum of 10 total spots are discounted to 950 Euros! Booking conditions for the ULTIMATE are different to the main event package, see the download package for more details.