# Open Water Swimming

Canonical HTML: https://effortsignal.com/features/open-water-swimming/

Last content update: 2026-09-14

Follow a swim beyond the pool: see the recorded route, read pace per 100 m, and compare changes in heart rate and stroke rate. Distance-based best efforts show where you sustained your fastest swimming within the session.

<!-- Open-water efforts derive from distance samples, not invented pool lengths; sensor and GPS limits stay beside the relevant evidence. -->
<p class="marketing-demo-note">Real EffortSignal web screenshots using a demo swim from 22 August: 3.8 km in 1:04:36. Activity analysis is included in Free and Pro.</p>

<h2 id="route">Start with the route and the session</h2>

The activity summary shows **distance**, **duration**, **pace**, **heart rate** and **stroke rate** when recorded. **Track map** places the GPS trace in context. Choose **Speed** or **Heart rate** to colour the track by a recorded metric.

<figure>

[![A loop in Lake Geneva is coloured by recorded swimming speed beneath the activity summary](/marketing/product/catalog-swim-open-water-desktop.webp)](/marketing/product/catalog-swim-open-water-desktop.png)

<figcaption>The example covers 3.8 km at an average 1:42 /100 m, with 148 bpm heart rate and 29 spm stroke rate. Map colours show variation along the recorded route.</figcaption>
<a class="marketing-image-enlarge" href="/marketing/product/catalog-swim-open-water-desktop.png">Enlarge the open-water route</a>
</figure>

A route requires recorded positions. Pace and best efforts depend on the source distance and speed data, so GPS errors can affect the result. The map shows the recorded track; it does not correct for currents or calculate a current-adjusted swimming pace.

<h2 id="pace-and-stroke-rate">Read pace and stroke rate together</h2>

**Overview** keeps heart rate first, followed by pace per 100 m. Select **Swimming** for the pace and **Stroke rate** charts. Stroke rate uses recorded cadence, in **spm**, so it can be shown even when the activity has no pool-length messages.

<figure>

[![The Swimming tab shows pace per 100 m and stroke rate throughout the open-water activity](/marketing/product/catalog-swim-stroke-rate-desktop.webp)](/marketing/product/catalog-swim-stroke-rate-desktop.png)

<figcaption>The same timeline makes it possible to see whether a change in pace coincided with a change in stroke rate.</figcaption>
<a class="marketing-image-enlarge" href="/marketing/product/catalog-swim-stroke-rate-desktop.png">Enlarge pace and stroke rate</a>
</figure>

Use **Heart rate** for its available charts and duration curve. Recorded cadence provides stroke-rate analysis even when stroke style or total stroke count is unavailable. Length counts and SWOLF require pool-length recordings.

<h2 id="best-efforts">Best efforts without pool walls</h2>

The swim pace curve and table cover **50, 100, 200, 400, 800 and 1500 m** within the activity. EffortSignal finds the fastest elapsed time over each distance using the recorded distance stream. Boundaries between nearby samples are interpolated; long gaps and distance resets are excluded.

<figure>

[![Open-water best efforts show a distance-based pace curve and times from 50 to 1500 m with Show on charts actions](/marketing/product/catalog-swim-open-best-desktop.webp)](/marketing/product/catalog-swim-open-best-desktop.png)

<figcaption>The example's 400 m effort is about 6:30, and its 1500 m effort about 25:17. These are estimates from recorded distance, not race-certified times. Phones show the pace curve; the full-size image includes the table.</figcaption>
<a class="marketing-image-enlarge" href="/marketing/product/catalog-swim-open-best-desktop.png">Enlarge open-water best efforts</a>
</figure>

Rest inside the chosen effort remains included. **Show on charts** highlights the effort without changing the zoom. If the recording has insufficient continuous distance for a result, that distance stays unavailable.

<h2 id="laps">Keep the laps your device recorded</h2>

Review imported laps in **Breakdown → Laps**. This swim has one lap covering the whole activity. Select a time range to inspect a particular part of the swim, or save it as an interval for closer analysis.

<h2 id="training-load">Count the swim alongside the ride and run</h2>

For triathletes, the open-water session belongs in the same training history as the other two sports. With **at least 90% heart-rate coverage** and applicable resting and maximum HR settings, swimming produces **TRIMP** and contributes to **Fitness (CTL), Fatigue (ATL) and Form (TSB)**. Recorded duration also appears in **Training Volume**, where the **Swimming** filter separates it from the combined total.

See [Swimming Analytics](/features/swimming-analytics/#training-load) for the load and volume screenshots, or [Pool Swimming](/features/pool-swimming/) for recorded lengths, stroke metrics and pool best efforts.

All Pro features are free through January 31, 2027. No credit card or automatic charges. After Early Access, keep using Free or choose Pro. [See Free and Pro plans](/pricing/).