Introduction

Swimming is one of the best activities for staying in shape, offering cardio, muscle building, and lung strengthening benefits. Whether you’re training in pools or open water, a swimming watch is a valuable investment to maximize your time and effort.

However, here’s the truth: no swim watch is perfect. While they promise cutting-edge tracking and advanced analytics, they all have limitations. Understanding these limitations while recognizing their value is key to making the most of your swimming watch.

Essential Features to Look For

Waterproof Rating

Your watch needs robust water resistance, not just splash protection. Look for ATM ratings:

• 10 ATM: Good for extended swims and diving
• 20 ATM: Withstands water impact (ideal for dive starts)
• 50 ATM: Suitable for deeper activities

Check that buttons work underwater and follow brand recommendations for saltwater use (Garmin suggests rinsing with fresh water after ocean swims).

Swimming-Specific Tracking

All swim watches track basic distance and time, but advanced features include:

• Lap counting with automatic turn detection
• Splits and time per length
• Stroke count and stroke recognition
• SWOLF scores (stroke count + time)
• Pace monitoring
• Training zones

Choose complexity based on your needs—basic lap counting requires simpler (cheaper) watches, while comprehensive metrics need multisport devices.

GPS for Open Water

Open-water swimming requires watches with dedicated open-water modes that use GPS for speed and distance tracking. This is crucial because:

• Open-water conditions vary significantly
• Wetsuits change swim speed
• Pool pacing is deceptive due to push-off advantages

GPS also enables swim playback with maps and 100m splits. Multi-band GPS improves accuracy in remote locations like lakes or quarries.

Pro Tip: Place your watch in a swim buoy for maximum GPS accuracy—constant satellite connection provides more detailed tracking.

Heart Rate Monitoring

Swim watches use optical sensors to track heart rate, but water creates challenges. For peak accuracy, invest in a chest strap—studies show wearables are significantly less accurate than chest straps for aquatic heart rate monitoring.

Heart Rate Challenges

Optical heart rate monitoring in water has 10-25% error rates because:

• Water bends light, interfering with blood flow detection
• Loose watches allow water between sensor and skin
• Cold water constricts blood vessels, causing false readings

Understanding Technology Limitations

Motion Sensor Accuracy

Your watch doesn’t measure actual distance—it detects movement patterns and estimates. Accelerometers and gyroscopes track speed and direction changes, registering wall push-offs as new laps and counting arm strokes.

Research shows stroke recognition accuracy varies:

• Freestyle: ~90% accurate
• Breaststroke/Backstroke: ~75-80% accurate

Factors causing errors include switching strokes mid-lap, long underwater glides, inconsistent rhythm, kickboard use, and drill variations. Notably, Apple Watch uniquely tracks kickboard training accurately.

GPS Limitations

GPS doesn’t work well underwater, so watches only record location when your arm breaks the surface. Your watch estimates movement between these points, but:

• Slow stroke rates = fewer GPS points = less accuracy
• GPS-based tracking can overestimate distance by 10-15%
• Choppy water disrupts signals
• Water distorts GPS accuracy

This explains why swim maps sometimes show erratic, zigzagging routes even when swimming straight lines.

AI Stroke Recognition Issues

Watches use pre-trained AI models comparing your movements to learned patterns. Freestyle detection works best, while breaststroke and backstroke cause more errors (~75% accuracy). Unique techniques, fatigue, or mid-lap stroke changes confuse the system.

Standout Options                                            

Apple Watch Series 8

Exceptional for pool accuracy with beautiful screen and comprehensive data. Unique ability to track kickboard work. Requires daily charging but provides unmatched lap counting precision.

Garmin Instinct 2

Excellent for multisport athletes wanting detailed analytics across activities. Strong GPS tracking and extensive third-party app support.

Samsung Active 2

Solid basic swim tracking with good water resistance, ideal for casual swimmers wanting general smartwatch features.

Making the Most of Your Watch

While no swim watch achieves 100% precision, they provide valuable training insights for non-professional swimmers. Use them to:

• Track progress trends over time
• Monitor training consistency
• Build workout motivation
• Understand efficiency patterns

Focus on long-term trends rather than perfect precision in individual metrics. Understanding what to trust (general patterns) versus what to question (exact distances, precise heart rates) maximizes value.

Third-Party Apps and Connectivity

Apple, Garmin, and Samsung offer extensive third-party ecosystems for loading workouts and joining swimming communities—valuable for structured training and motivation.

The Bottom Line

Swimming watches are powerful training tools when you understand their capabilities and limitations. Choose based on your specific needs: basic lap counting for pool training or comprehensive GPS tracking for open-water adventures.

Remember that technology limitations don’t negate value—they simply require realistic expectations. Use swim watch data as part of a broader training approach rather than absolute truth. The right watch with proper understanding becomes an invaluable tool for achieving your aquatic goals.

Whether you’re counting laps in the pool or navigating open water, a quality swim watch helps track progress, maintain motivation, and optimize training effectiveness. The key is matching the watch to your swimming style and understanding how to interpret its data meaningfully.