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Swimming · 16 weeks16-week 5 km open water swim training plan
A 16-week 5 km open water swim training plan takes a swimmer who does 400 m in 7:30, about 4 km a week from where they are to race day in 17 weeks, building to 2h23 of training in the biggest week. It spends 7 weeks in base, 7 weeks in build, 2 weeks in peak, with 3 lighter weeks to absorb the work, on 6 days a week.
Build my 5 km open water swim plan — freeBuilt from your own numbers and your own week. The first week is free.
16 weeks is a comfortable length for a 5 km open water swim. There is room for a proper base before the harder work, lighter weeks to absorb it, and a taper that leaves you fresh rather than flat.
How long the 5 km open water swim takes
Predicted open-water time over 5 km, by Critical Swim Speed. Open water is slower than the pool — no walls to push off, sighting, and a line that is never quite straight — and the prediction allows for it.
| Your CSS per 100 m | Predicted finish |
|---|---|
| 1:35 | 1:23:55 |
| 1:45 | 1:32:45 |
| 2:00 | 1:46:00 |
| 2:15 | 1:59:15 |
| 2:30 | 2:12:30 |
At 5 km and beyond, fuelling becomes part of the swim. Practise taking a drink or a gel while treading water in training — the first time should not be race day — and expect the second half to be decided by how well you held your stroke together when tired.
What the weeks are for
| Base | 7 weeks — aerobic volume, mostly easy, the foundation everything else stands on |
|---|---|
| Build | 7 weeks — the harder sessions arrive and volume keeps climbing |
| Peak | 2 weeks — the biggest, most race-specific weeks |
| Lighter weeks | 3, roughly every fourth week |
| Total | 50 hours |
The 17 weeks
Generated for a swimmer who does 400 m in 7:30, about 4 km a week.
| Week | Phase | Hours | Load | |
|---|---|---|---|---|
| 1 | Base | 3h 08 | 82 | |
| 2 | Base | 3h 08 | 82 | |
| 3 | Base | 3h 08 | 82 | |
| 4 | Base · down | 2h 35 | 48 | |
| 5 | Base | 3h 08 | 82 | |
| 6 | Base | 3h 08 | 82 | |
| 7 | Base | 3h 08 | 82 | |
| 8 | Build · down | 2h 41 | 56 | |
| 9 | Build | 3h 18 | 96 | |
| 10 | Build | 3h 18 | 96 | |
| 11 | Build | 3h 18 | 96 | |
| 12 | Build · down | 2h 41 | 56 | |
| 13 | Build | 3h 18 | 96 | |
| 14 | Build | 3h 18 | 96 | |
| 15 | Peak | 2h 23 | 101 | |
| 16 | Peak | 2h 23 | 101 | |
| 17 | Race · race | 2h 16 | 185 |
The biggest week, session by session
Week 15, peak phase — the heaviest week of the block.
| Monday | Technique and drills — 0h35, 2 km |
|---|---|
| Tuesday | Open water — 0h44, 2 km |
| Sunday | Strength — lower body — 0h27 |
| Sunday | Speed — 8 × 100 m — 0h37, 1.8 km |
The swim paces
| Critical Swim Speed | 1:59 per 100 m |
|---|---|
| Recovery | 2:09/100 m — Easy enough to think about your stroke rather than your lungs. |
| Endurance | 2:04/100 m — Steady. You could keep going for a long time. |
| CSS | 1:59/100 m — Threshold. Hard but repeatable across a whole set. |
| VO₂max | 1:56/100 m — Faster than threshold, in short reps with real rest. |
| Speed | 1:53/100 m — Short and quick. Technique first, effort second. |
From a 400 m in 7:30 and a 200 m in 3:32, using the two-trial protocol (Wakayoshi et al., 1992). Your own CSS comes from your own two swims.
What this plan says out loud
Worth saying plainly about swimming: for most amateur swimmers, improvement comes from technique rather than fitness. This plan can prescribe the work. It cannot see that your hips are sinking or your catch is dropping, and no amount of threshold sets fixes a stroke. If you can afford one thing, buy a few sessions with a coach on the pool deck rather than more sets from us.
You are starting from a low base, so the first few weeks are deliberately modest. Consistency now is worth more than any single session.
Some sessions have been cut to fit the time you said you have — 45 minutes on a weekday and 60 at the weekend. That is a real constraint and the plan respects it, but be aware the long session is the one that matters most: if you can find more time anywhere, find it on the weekend.
Common questions
Is 16 weeks enough for a 5 km open water swim?
Yes, for most people who already exercise. We would choose at least 12 weeks, and this is 16.
How many days a week does it train?
6, on Monday, Tuesday, Wednesday, Friday, Saturday, Sunday in this example. You tell the plan which days you actually have, and it never puts two hard days back to back.
What is the longest session?
Open water, about 0h44. It is capped by share of the week, by absolute length, and by the time you say you have.
Can I use this if I train at altitude?
Yes, and you should say so when you build it. Paces and power are corrected for the difference between where you tested and where you train — in Johannesburg that is roughly 8%, or about 26 seconds a kilometre on an easy run for a 20-minute 5 km runner.