Garmin Forerunner 165 Open Water Swimming Guide
Can the Garmin Forerunner 165 handle open water swimming? Here is how its GPS, stroke rate, and open-water metrics perform in lakes and oceans.
The Garmin Forerunner 165 has a dedicated open water swim profile. It tracks GPS distance, pace per 100 m, stroke rate, and heart rate for swims in lakes, rivers, and the ocean, then syncs the full map trace and splits to Garmin Connect. For most amateur open water swimmers, that is genuinely enough. The catch — and the reason this guide exists — is that the 165 uses single-band GPS, lacks maps, and quietly drops some pool-mode features the moment you switch profiles.
Knowing exactly where it is strong, where it drifts, and where you should reach for a different watch saves a 30-minute swim logging as 1.2 km when you actually swam 1.5 km.
This is the open-water-specific companion to our broader Garmin Forerunner 165 swimming review . If you only want the pool lap counting, stroke detection, and daily-wear verdict, read that one first. If your main use case is a lake, a river, or an ocean swim, keep reading — the two watches are the same, but the open water story deserves its own page.
Setting Up the Open Water Profile
The open water profile is hidden by default on a fresh 165. Press and hold the Light button, scroll to Add Activity, and pick Open Water Swim from the list. Once added, it appears as a quick-start tile on your activity list alongside Pool Swim, Run, and Bike.
Before you start, set the data fields you want in Garmin Connect Mobile or on the watch under Activity Settings → Data Screens. Useful fields for an open water swim are:
Wait for a green GPS fix before pressing start. Open water tracks always begin from a cold GPS start because the watch has no recent pool fix to lean on, so expect 15–45 seconds for the fix on a clear day. If the watch flashes a Weak GPS signal warning, walk to open sky or wait another minute — starting early is the #1 cause of bunched-up tracks at the swim start.
What the Forerunner 165 Records During an Open Water Swim
Once the activity starts, the 165 logs the following into the FIT file at one record per second:
Two pool-mode metrics do not carry over. SWOLF is per-length and does not appear outside the pool — you cannot compare open water efficiency to your last pool session using SWOLF. Lengths, turns, and lap splits are also pool-mode only. If you need structured rest intervals in open water, you have to use elapsed time and mental send-offs, not the watch.
GPS Accuracy in the Real World
The single-band L1 GPS in the 165 is the feature most swimmers will notice first in open water — sometimes for the wrong reasons. In a wide, calm lake with open sky above, distance totals land within 2–4% of a measured course, and the map trace in Garmin Connect is close to where you actually swam. Pace per 100 m looks believable across a full session.
Problems show up in three places:
None of these are unique to the 165 — every single-band swim watch has the same trade-offs. They only become a real problem if you need sub-3% distance accuracy for race splits, or if you swim in a reflective environment often. For most casual and amateur open water training the 165 is fine. For the upgrade path see the section below.
Sighting and Open Water Technique With the 165
The watch is a data tool, not a navigation tool — repeat that to yourself before any open water swim. For real sighting technique, read our open water sighting drills guide , which walks through the crocodile-eyes sighting, bilateral breathing patterns, and landmark selection that get you back to shore.
With the 165 on your wrist, use sighting cycles to glance at the data screen if you want pace or distance mid-swim. Be deliberate: looking at your watch every stroke drops your stroke rate and your line. A useful pattern is to sight a landmark, breathe right, glance at the watch for pace only on the third stroke of every 20-stroke cycle. That keeps your sighting independent of your data review.
If open water makes you nervous at all, the single biggest thing you can do is read our open water panic reset guide before your next swim. Anxiety, not watch accuracy, is what ends most open water sessions early.
Battery, Display, and Cold-Water Considerations
The 165 is rated for up to 11 hours in GPS mode, which covers virtually any amateur open water swim — even an Ironman swim leg plus the entire bike and run fits comfortably in that envelope, though you would probably want the 570's multisport transitions for that. For pure open water swims of 30 minutes to 4 hours, the battery is a non-issue.
The AMOLED display is bright enough to read in direct sunlight, which matters for open water sighting looks. Wet finger taps are less responsive than a dry screen, so if you set auto-lap or rest timers via touch, double-press the physical Start button instead. The watch also warms up with your wrist — cold water below 10°C tightens the strap fit and can drop the OHR sensor contact until your wrist warms the sensor back up.
A chest strap solves that entirely.
Rinse the watch with fresh water after ocean swims. Salt build-up under the OHR sensor window is the leading cause of phantom HR readings on Garmin watches after a few months of sea swims — 30 seconds under a tap prevents it.
When to Step Up: 265 and 570 for Open Water
The 165 is the right answer for most open water swimmers. Step up if any of the following is true:
For a deeper comparison across the whole Garmin lineup for swimmers, see our best Garmin watch for swimming guide . If you split your time between swimming and running, the best Garmin for swimming and running guide covers the dual-sport trade-offs.
Train Your Open Water Swims With AquaPlan
The 165 logs the swim — AquaPlan plans it. Build open water and pool sessions in the workout generator, export a Garmin FIT file, and follow your intervals from your wrist. Or start from 130+ ready-made workouts sorted by goal and training zone, including open water pace targets and CSS-based sets.
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Written and maintained by AquaPlan Team, Swim Training & Product.
The AquaPlan team builds swim-training software for structured pool workouts, Garmin-compatible FIT export, printable workout PDFs, and progress tracking.
Focus areas: Structured swim workout design, Garmin-compatible FIT file export, Pool training plans and workout-library systems, Swim training tools for web, iOS, and Android.
Editorial standard: AquaPlan training guides are checked against the current workout builder, workout library, Garmin export workflow, and product limits before publication.