On Friday, I will start swimming 33.3 kilometres around and across Lake Geneva.

Not all at once, thankfully. UltraSwim Switzerland divides the distance into a series of swims over four days. Even so, it is long enough that the usual pre-event questions have started appearing in the 33.3 forums.

What are your taper-week swims?

How are you fuelling?

What pace are you targeting?

These are all sensible questions. But after completing three 33.3 events, I increasingly think they may be questions for swimmers doing a rather different event from me.

They are planning to run the hills.

I am planning to hike them.

Swimming takes place in a dense medium, and that changes the relationship between effort and speed. The drag acting on a swimmer rises roughly with the square of velocity. The power needed to overcome it rises even more sharply.

Swimming only a little faster can therefore require disproportionately more effort.

In that sense, swimming has something in common with running uphill. On a flat road, almost everyone runs. Put the same people on a sufficiently steep hill and the calculation changes. Some runners can keep running efficiently, while others reach a point where running demands much more effort but produces very little additional speed.

A strong, purposeful hike becomes the better option.

The strongest swimmers may be able to keep running the hills.

Most of us should not.

At least, not for very long.

Swimmers are often given a CSS value from a test. It is a useful number, but it is easy to give it too much authority. CSS is not your comfortable, all-day swimming pace. It is an estimate of the fastest pace you can sustain without the rapid fatigue associated with swimming above your critical speed.

In the hill-running analogy, CSS is fast running.

You can hold it for a test. You can build training sets around it. You may be able to complete substantial intervals somewhere near it. None of that makes it an intelligent pace for several long open-water swims across four days.

A highly developed swimmer can stay relatively close to CSS because their technique remains stable as effort rises. Their body position stays good, their catch remains connected, and the extra effort continues to buy meaningful speed.

For a developing swimmer, the relationship can be very different. As they push harder, breathing becomes more urgent, balance deteriorates, the stroke becomes less effective, and each extra unit of effort buys less forward movement.

They are still going faster.

Just not fast enough to justify the cost.

This is what makes an event such as UltraSwim 33.3 interesting. On paper, everyone is completing the same distance. In practice, they may be doing very different events.

Some swimmers are racing. They are operating close enough to their physiological and technical limits that pacing, tapering, fuelling and recovery become important performance variables. A slightly poor taper may leave them flat. A feeding error may cost them late in a stage. A pace that is only a little too ambitious may create a large recovery bill before the next swim.

For them, optimisation matters.

Then there are the hikers.

That includes me.

My aim is not to extract every possible minute from each stage. It is to settle into an easy rhythm, keep the stroke quiet, finish each swim comfortably and remain genuinely willing to do it again the following morning.

A swimming hike is not lazy swimming. Good hiking is purposeful. It has posture, rhythm and forward intent. The effort is controlled, but the movement is not passive.

The same is true in the water.

The right hiking pace is probably the fastest pace at which the stroke remains calm and repeatable. Breathing stays controlled, technique does not require constant correction and fuelling remains simple. You finish with the sense that you could have continued and, most importantly, that you can produce something similar tomorrow.

That pace may sit much farther below CSS than expected. A swimmer with a CSS of 1:40 per 100 metres might look at 1:48 or 1:50 and assume that must be easy.

It may not be.

That may still be running.

Their hiking pace might be 1:58, 2:05 or slower once sighting, chop, temperature and accumulated fatigue are added. The precise number matters less than the shape of the effort. You are looking for the point beyond which swimming harder creates substantially more fatigue but very little useful speed.

This distinction changes how I think about the final week.

I do not need to discover the perfect taper. I need to arrive healthy, rested and accustomed to swimming frequently.

I do not need to derive a target pace for every stage. I need to find a rhythm that feels almost suspiciously easy and stay there.

Nor do I need to force down 90+ grams of carbohydrate per hour simply because that figure appears in endurance-sport discussions. Across three previous 33.3 events, I have taken carbohydrates and drink at the provided feed stations during the swims, then eaten properly between stages.

That may not support someone racing close to their limit. It has been enough for me because the intensity has remained low enough that I have not needed a high-rate fuelling strategy merely to sustain it.

I am not trying to run the hill.

I am hiking it.

None of this makes 33.3 kilometres easy. The shoulders still perform thousands upon thousands of repetitions. Cold, sun, chop, poor sleep and cumulative fatigue do not disappear because you choose an easier pace. You can still become injured, depleted or unwell while moving slowly.

But easier pacing creates margin, and margin is valuable. It helps preserve technique, simplifies fuelling, reduces the recovery cost between stages and leaves more options when conditions become difficult.

The goal is not optimisation.

It is continuity.

There is also a longer-term training point here. The goal is not merely to become fit enough to tolerate more effort. It is to make the water less steep.

Better balance reduces drag. A better body line reduces the amount of water you need to displace. A more connected stroke converts more of your effort into forward movement. Greater durability allows those qualities to survive for longer.

The more economical swimmer is not only producing more power.

They are facing a shallower hill.

Over time, their hiking pace becomes faster. A speed that once felt like running becomes economical. A stroke that once required constant attention becomes increasingly automatic.

That is probably the most useful objective for a developing ultra swimmer. Not to hold a higher percentage of CSS, but to improve until an easier effort produces more speed.

There is an uncomfortable reality hidden inside the metaphor. The slowest swimmers often face the steepest hills. Poorer balance, greater drag and less effective propulsion mean they may be moving more slowly while working every bit as hard.

Calling it hiking is not a way of diminishing that effort. Quite the opposite.

When I reach the finish line, I know that some swimmers behind me will have spent far longer in the water, overcoming a steeper hill for every kilometre. I respect that enormously.

A lot of ultra-swimming advice is written for people trying to run the hill. It may be excellent advice. It may simply be solving a different problem.

The racer asks: how do I optimise this performance?

The hiker asks: how do I keep this easy enough that I can do it again tomorrow?

Both are legitimate. You just need to know which event you are doing.

On Friday, some swimmers will race in Lake Geneva.

I will be hiking.

And, until then, I can chill.