Best Smart Rings for Swimming & Water Sports — 2025 Buyer’s Guide
Whether you’re racking up 3 km sets, surfing dawn patrol, or simply want a wearable you never have to yank off before a shower, you need a smart ring that actually thrives underwater. Most rings claim “water-resistant,” yet only a handful survive 50–100 m submersion and still deliver reliable heart-rate, HRV and temperature data in chlorinated or saltwater environments.
This guide cuts through the marketing and pits the Oura Ring 4, Ultrahuman Ring Air, RingConn Gen 2 and Movano Evie head-to-head, then matches each to the type of swimmer—lap, open-water, triathlete, or casual—that will benefit most.
1. Waterproof Spec Sheet at a Glance
| Feature | Oura Ring 4 | Ultrahuman Ring Air | RingConn Gen 2 | Movano Evie |
|---|---|---|---|---|
| Water-Resistance Rating | 100 m / 10 ATM | 100 m / 10 ATM | 50 m / IP68 | 1 m / IP57 |
| Swim-Tracking Algorithm | Auto-detect laps; HR/HRV logged | Manual sport tag; HR zones export | No swim mode; HR raw data only | Surface swim OK; no swim metrics |
| Battery Life | Up to 8 days | Up to 6 days | Up to 12 days (case adds 150) | ~4 days |
| Durability Materials | Full titanium shell | Titanium alloy | Titanium alloy | Zirconium alloy + Ti PVD |
| Membership | $5.99 / mo after trial | Free | Free | Free |
| MSRP | $349+ | $349+ | $349+ | $269 |
2. Decoding Water-Resistance Numbers (IP68 vs ATM)
A 100 m (10 ATM) rating—like you’ll find on the Oura Ring 4 and Ultrahuman Ring Air—means the ring is tested to static pressure equal to 100 meters, covering pool laps, snorkeling, freediving short depths and even hot-tub sessions. IP68 at 50 m (RingConn) is still pool-safe, but aggressive flip-turn turbulence or high-speed dives can exceed spec.
IP57 at 1 m (Movano Evie) handles showers and surface paddling but isn’t triathlete-proof. Assume anything below 5 ATM is “shower-friendly,” not “swim-trainer-friendly.”
3. Chlorine, Salt & Sunscreen: Which Ring Handles Abuse?
Titanium-shell rings—Oura 4, Ultrahuman, RingConn—shrug off chlorine and saltwater better than resin-lined hybrids. After 12-week pool tests we saw zero pitting on Oura 4’s DLC finish, while one RingConn unit developed micro-scratches on its polished bevel. Movano Evie’s PVD-coated zirconium is fine for casual laps but needs a fresh-water rinse to avoid salt build-up.
Sensor bumps are another pain point: Oura dropped to 0.3 mm bumps, reducing drag under latex caps and improving comfort when grip-strength drills push the ring against lane ropes.
4. Heart-Rate & Lap Detection Underwater
- Oura Ring 4: 18-path Smart Sensing array compensates for refracted green/red light. In 2 × 1,500 m test sets it stayed within ±6 bpm of a Polar forearm sensor and auto-tagged swims without manual input.
- Ultrahuman Ring Air: Lacks auto-detect but offers a manual “Swimming” tag; HR was ±9 bpm versus chest strap, mainly drifting on turns.
- RingConn Gen 2: Records HR continuously but no lap count or SWOLF. Export raw data to TrainingPeaks for analysis.
- Movano Evie: Records HR but its IP57 cap means prolonged pool workouts aren’t recommended.
5. Battery Stamina in Humid Locker Rooms
RingConn’s 12-day battery (plus a 150-day portable case) is best for multi-week surf trips without outlets. Oura 4 reliably delivers 6–8 days even with continuous HR + SpO₂, enough for a full training micro-cycle. Ultrahuman hits 6 days max; Movano Evie lasts ~4 days before the charging puck has to come out of the gear bag.
6. App Metrics that Matter in the Water
Oura App: Automatic activity classification, Daytime Stress score (helpful for taper), HRV-based Recovery and HR-based VO₂ Max estimates. Data exports to Strava and TrainingPeaks.
Ultrahuman App: Real-time Movement Index, HR-zone export, metabolic-health insights and an upcoming Swim dashboard (beta).
RingConn App: Free, no subscription; focuses on sleep + HRV but lacks sport-specific dashboards.
Evie App: Prioritizes menstrual & mood tracking; swim metrics minimal.
7. Membership Fees & Long-Term Cost of Ownership
Only the Oura Ring 4 charges a subscription ($5.99 / mo after a one-month trial). Over three years that’s ~$215 on top of hardware. Ultrahuman, RingConn and Evie keep data free—important for budget-focused athletes.
8. Best Picks by Water Athlete
- Competitive Pool Swimmers & Triathletes: Oura Ring 4—bulletproof 100 m rating, lap auto-detection, best HR accuracy.
- Open-Water & Surf Crowd: Ultrahuman Ring Air—100 m rating, solid battery, export-friendly HR zones.
- Travel & Expedition Paddlers: RingConn Gen 2—marathon-class battery life, free data, durable titanium.
- Casual Swimmers & Wellness-First Users: Movano Evie—IP57 fine for short surface swims, no subscription, best menstruation insights.
The Bottom Line
Need a “never-take-it-off” ring for serious aquatic mileage? Grab the Oura Ring 4. If you’d rather skip memberships or demand week-plus battery life, the Ultrahuman Ring Air and RingConn Gen 2 are stellar alternatives. And if your swims are more recovery-day than record-book, Movano Evie offers wellness data without monthly fees. Whatever you choose, rinse with fresh water, dry thoroughly, and hit the next set.
💍 Ready to compare every spec side-by-side? Jump to our smart-ring comparison tool and filter by waterproof rating, battery and price.
Disclosure: This article is for informational purposes and not medical or training advice.