
Garmin
The endurance king — Fenix 8 with solar power

Oppo
A week-long-battery budget smartwatch
Garmin Fenix 8 Solar
Garmin Fenix 8 Solar
Garmin Fenix 8 Solar
Adventure-flagship design in 47mm and 51mm. Fiber-reinforced polymer or titanium, Sapphire crystal options. Leak-proof metal buttons. Five-button + touchscreen. Built-in LED flashlight.
Oppo Watch S
TechTalkTown may earn a commission from purchases made through links below. As an Amazon Associate I earn from qualifying purchases. This does not influence our reviews. Learn more.
Oppo Watch S
Oppo Watch S
The Oppo Watch S's headline is how little there is of it — a round ~45mm watch just 8.9mm thick and around 35g without the strap, built around a stainless-steel mid-frame. Reviewers say it nearly disappears on the wrist.
Garmin Fenix 8 Solar
MIP (memory-in-pixel) transflective display with Power Glass solar charging. Exceptionally sunlight-readable and power-efficient — but not vivid or colorful like AMOLED.
Oppo Watch S
A 1.46-inch round AMOLED at 464 x 464 (317 ppi). It can hit a brilliant 3,000-nit peak — but only automatically, in Oppo's workout modes under strong sunlight. In everyday use it's capped at 600 nits, with a 1,500-nit high-brightness mode.
Garmin Fenix 8 Solar
Elevate Gen 5 optical HR with skin temperature, SpO2, HRV Status, Body Battery, sleep tracking, Morning Report. ECG support. Garmin's latest sensor generation.
Oppo Watch S
For a budget watch the Oppo Watch S carries a serious sensor array — an 8-channel optical heart-rate sensor, a 16-channel SpO2 sensor, ECG electrodes and a skin-temperature sensor — anchored by a 60-second check that reads around 14 health indicators at once. ECG availability depends on regional certification.
Garmin Fenix 8 Solar
Garmin's deepest training-science suite — Training Readiness, Endurance Score, Hill Score, Acute/Chronic Load, full multisport + triathlon modes. The serious-athlete benchmark.
Oppo Watch S
The Oppo Watch S covers 100+ workout modes with built-in GPS and an AI sports coach that gauges readiness from HRV and recent training load. It's a capable everyday fitness tracker — though there's little independent accuracy testing to confirm how it stacks up.
Garmin Fenix 8 Solar
Up to ~48 days in always-on smartwatch mode with solar — the longest battery of any Fenix 8. Solar charging extends runtime further in sunlight. Proprietary USB-C charging.
Oppo Watch S
The Oppo Watch S's strongest card. Oppo rates the 330mAh battery at up to 10 days maximum, 7 days typical and about 4 days with the always-on display on — and fast charging adds a full day in 10 minutes, with a complete charge in roughly 75-90 minutes.
Garmin Fenix 8 Solar
Garmin OS + Garmin Connect + Connect IQ store. Built-in speaker + microphone (NEW for Fenix) for voice calls + voice assistant. Garmin Pay. Works with iOS + Android.
Oppo Watch S
The Oppo Watch S runs ColorOS Watch 7.1 on a power-efficient BES2800BP chip with 4GB of storage — not Wear OS. That choice is the reason the battery lasts a week, but it also means no Google Play app store and a simpler, more limited software experience.
Garmin Fenix 8 Solar
Dive-rated water resistance + MIL-STD-810 testing. Fiber-reinforced polymer or titanium, Sapphire crystal options. Leak-proof buttons. Built for serious expedition and underwater use.
Oppo Watch S
The Oppo Watch S is rated 5 ATM plus IP68 (and IP69), with Splash Touch that keeps the screen usable when wet. It's fine for swimming and everyday water — but Oppo specifically warns against hot showers, saunas and diving.
Garmin Fenix 8 Solar
Multi-band (dual-frequency) GPS, full-color TopoActive maps, NFC for Garmin Pay, Bluetooth, ANT+, Wi-Fi. No LTE (that's the Fenix 8 Pro's domain).
Oppo Watch S
Built-in GPS, Bluetooth, Wi-Fi and NFC cover the everyday essentials. There's no cellular model, so the Oppo Watch S relies on a paired phone for connectivity.
Garmin Fenix 8 Solar
$1,099-$1,199+ launch. The endurance-maximized adventure flagship. Competes with the Fenix 8 AMOLED, the Apple Watch Ultra, and the Coros Vertix. Ages well and holds value.
Oppo Watch S
The Oppo Watch S launched at around $399 NZD (roughly $230 USD) and is not officially sold in the US. For the price it's a strong value — week-long battery, ECG, a premium-feeling build — as long as you accept the simpler ColorOS platform.