Both the Sony NW-WS413 and the Finis Swimp3 have been around for years. They're not flashy. You load music manually like it's 2009 — no streaming, no app. For a certain type of swimmer, that's exactly the point: reliability, simplicity, no subscription. But which one is the better buy?
Sony NW-WS413 wins overall: better battery (12 hrs vs 7), more versatile design (works without goggles), and longer durability track record. The Finis Swimp3 wins specifically on underwater sound clarity — if that's your priority, it delivers. Neither is the best swimming MP3 player in 2026 — see our full comparison for the current top pick.
Quick Specs Side by Side
| Spec | Sony NW-WS413 | Finis Swimp3 |
|---|---|---|
| Price | ~$60–80 | ~$60–70 |
| Storage | 4 GB | 4 GB |
| Battery | 12 hours | 7 hours |
| Waterproof | IPX5/IPX8 | IPX8 |
| Sound tech | In-ear drivers | Bone conduction |
| Wear style | Wraparound, behind head | Goggle-clip |
| Bluetooth | ✓ Yes (out of water) | ✗ No |
| Works without goggles | ✓ Yes | ✗ No |
| Weight | ~33g | ~28g |
Sound Quality
This is where they take completely different approaches — and the difference matters a lot for swimmers.
Sony NW-WS413: In-ear drivers Sony wins above water
The Sony uses small drivers positioned near the ear canal. Above water it sounds decent — not audiophile quality, but perfectly fine for workouts. Underwater, sound degrades noticeably. You'll hear it, but clarity drops during active swimming, particularly during flip turns and bilateral breathing when water pressure breaks the ear seal. Bass holds up better than treble.
Finis Swimp3: Bone conduction via goggle strap Finis wins underwater
The Swimp3 transmits sound through your cheekbones via the goggle strap contact point. Underwater, this actually works better than in-ear options — the signal travels through solid material rather than air, so water pressure can't degrade it. The sound is thinner and less bass-heavy than in-ear audio in air, but it stays consistent whether your head is above or below the water.
If underwater sound clarity is your single deciding factor, the Finis Swimp3 wins this category clearly.
Fit & Comfort
Sony NW-WS413 Draw
The Sony wraps around the back of the head and sits just outside the ear canal. It's designed to work with swim caps and goggles, though fitting all three together takes some adjustment. The unit is light at ~33g. Some swimmers report it shifting during tumble turns — it's not foolproof, but it's generally secure for freestyle and backstroke at moderate intensity.
Finis Swimp3
The Swimp3 clips directly onto the goggle strap at the temple. If your goggles fit well, this tends to stay securely in place. The limitation: you cannot use it without goggles. If you train without goggles, or your goggles have unusual strap geometry, the clip may not fit properly.
Both require trial and error to dial in the fit. Neither is perfect immediately out of the box.
Battery Life Sony wins
Sony claims 12 hours; real-world testing lands around 9–10 hours consistently. You could swim every day for a week without charging.
Finis claims 7 hours; real-world sits closer to 5–6 hours. Still enough for most training sessions, but notably shorter than the Sony.
For most swimmers doing 60–90 minute sessions, both batteries are adequate. The Sony's advantage matters primarily for marathon or ultra-distance swimmers, or those who simply hate charging gear frequently.
Loading Music
Both devices require you to drag and drop MP3 files via USB. No streaming, no app. If you're comfortable doing this, it takes two minutes. If you've never done it before, there's a small learning curve — but nothing difficult.
Sony uses a proprietary magnetic charging and sync cable. Lose it and you can't sync or charge until a replacement arrives. Finis uses standard micro-USB for charging (check your specific version for data transfer method).
Neither is as convenient as a streaming device. That's the trade-off for simplicity and reliability in the water.
Durability Sony wins (slightly)
The Sony NW-WS413 has a solid track record. Units regularly last 3–4 years with regular pool use. Chlorine resistance is reasonable and the wraparound design means fewer small components that can break.
The Finis Swimp3 is also well-built, but the goggle clip mechanism is the most common failure point reported by users — it can wear out over time, particularly with frequent daily on/off cycles. If you clip and unclip it every session, expect this to eventually loosen.
Who Should Buy Which
Buy the Sony NW-WS413 if:
- You want longer battery life with less frequent charging
- You also use the device outside the pool — commuting, gym, running
- You prefer a self-contained unit that doesn't depend on your goggles
- You don't always train with goggles
Buy the Finis Swimp3 if:
- Underwater sound clarity is your primary concern
- You always swim with goggles and the clip design doesn't bother you
- You want the most consistent audio when your head is fully submerged
Worth Considering: Step Up to SONR Music
Both devices have real limitations — here's the context
The Sony struggles with underwater clarity. The Finis requires goggles, has shorter battery, and no Bluetooth. Both have only 4 GB storage. For $50–70 more, the SONR Music gives you: 16 GB storage, true IPX8 bone conduction audio that works at any depth, fits under a swim cap, is wire-free, and includes Bluetooth for dryland use. If you're swimming regularly and want to invest once rather than upgrade later, it's worth considering.
See SONR Music on Amazon →