Why a four day 33.3km is the natural next challenge

The jump from 10km to 33.3km sounds huge, but split across four days it is four swims of 4 to 10km, a distance many Oceanman swimmers already cover in training.

See the four day format

The training is an extension of what you already do. Keep your aerobic base, add a longer weekly swim, and build comfort with back to back days so that swimming the morning after a hard effort feels normal. Practise feeding on the water and pacing conservatively. The free UltraSwim 33.3 seventeen week plan lays it out, and the affiliate coach network can tailor it. Because each event day is 4 to 10km, close to a familiar race distance, you are never asked to do something you have not effectively done before. You simply do it four days running, in warm water, with a boat beside you.

Each day runs under full boat and kayak cover with feeding on the water, so stepping up to the distance never means stepping into the unknown.

See the 2026 calendar

Every UltraSwim 33.3 group swims with two safety boats and two kayaks alongside, GPS tracking and on water feeding, with a medical and physio team on site each day. That level of cover is what lets swimmers of a wide range of speeds take on 33.3km with confidence, knowing help is always a few metres away.

Two boats, two kayaks per group · GPS tracking and feeding · Medical and physio on site

On the water · Explore safety

The 5 or 10km Oceanman swimmer is operationally ready for UltraSwim 33.3 today. The distance per day is below your Oceanman volume. The change is psychological more than physical. Four days of staged swimming requires recovery discipline, sleep hygiene, eating to refuel rather than enjoying the dinner, and pacing across the week rather than across a single race. Most Oceanman 5 or 10km finishers underestimate the recovery demand. The 21km Oceanman swimmer is already comfortable with the volume. Our preparation programme adds 6 to 8 months of structure for swimmers stepping up from a 5km background.

10km finishers ready now · 21km finishers comfortable with volume · 5km finishers you can build up over several months no problem

Step up readiness · See 2026 events

Watch finishers describe the moment they decided a single race was not enough, and what the four day format gave them.

From 1,794 euros, an UltraSwim 33.3 package covers four days of supported swimming, luxury hotel accommodation, breakfasts and refuel lunches, transfers, a preparation programme and the finisher experience. It is designed so that once you arrive, everything is taken care of and all you have to think about is the swimming and the people you meet.

All inclusive from 1,794 euros · Hotel, meals and transfers · Preparation programme included

All inclusive · See pricing

Go deeper on the format, training and the events

What is UltraSwim 33.3 · The format · Captain Webb and Trudy Ederle legacy · All events

Dates, packages, water temperatures and everything that is included, in one download to help you plan.