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Product Information
The SeaLife ReefMaster RM-4K (SL350) is an ultra-compact underwater action camera built for divers and snorkelers who want 4K video and sharp stills without carrying a bulky rig. It pairs a 14MP Panasonic CMOS sensor with a 140° wide angle fisheye lens, records 4K video at 30fps or 1080p at 60fps, and the removable inner camera sits inside a robust housing rated to 130 ft / 40 m with a thumb-screw "Pressure-Lock" seal.
Who it is for
The RM-4K suits divers, snorkelers and travelers who want a pocket-sized camera they can operate one-handed, mount to a light tray, and pair with a Sea Dragon photo-video light for reef, wreck or macro scenes. The simple 4-button control system and fixed-focus lens make it a practical choice for divers who want straightforward point-and-shoot operation underwater rather than a full manual camera system.
Key details
- Sensor and lens: 14MP Panasonic CMOS sensor with a 140° fisheye lens, 14mm 35mm-equivalent focal length, f/2.8 aperture.
- Video and stills: 4K at 30fps, 1080p at 60fps, with electronic image stabilization and underwater color correction for deep and shallow conditions.
- Waterproof rating: 130 ft / 40 m, sealed with a thumb-screw Pressure-Lock closing system.
- Display: 2" color TFT LCD screen.
- Memory: expandable with Micro SDHC/SDXC cards up to 128GB; Class V30 (U3) cards recommended for 4K recording.
- Battery: removable 900 mAh / 3.8V Li-ion battery delivering 2+ hours of video or 500+ still images.
- Weight: 7.1 oz / 202 grams for the housing with inner camera and battery installed.
Compatibility and sizing
The RM-4K is also offered as the RM-4K Pro 2000 Set (SL354), which bundles the same camera and housing with a Sea Dragon 2000F photo-video light. The housing mounts to a standard light tray and accepts SeaLife accessories including a spare battery (SL3504), screen shield (SL3506), Moisture Muncher drying capsules (SL911) to prevent internal fogging, and a Micro Wide Angle Dome Lens (SL052).
DiveCatalog.com is an authorized SeaLife dealer and a dive shop in Irvine, California since 2003. Call 888-701-4017 or chat with us if you have questions about fit, accessory compatibility or pairing the RM-4K with a Sea Dragon light.
- 14MP Panasonic CMOS sensor captures sharp, colorful still images underwater.
- 140° fisheye lens lets you get close to your subject while keeping the full scene in frame.
- 4K/1080p video records 4K Ultra HD at 30fps and 1080p HD at 60fps.
- Pressure-Lock thumb-screw seal secures the housing's O-ring without tools.
- Underwater color correction offers Deep and Shallow modes tuned for diving and snorkeling conditions.
- Electronic image stabilization reduces hand shake and vibration during video recording.
- Simple 4-button control keeps camera operation and menu navigation easy underwater.
- Expandable memory accepts Micro SDHC/SDXC cards up to 128GB, with V30 (U3) recommended for 4K.
- WiFi image and video transfer works with the free ReefMaster app for iOS and Android.
- Waterproof to 130 ft / 40 m for recreational dive depths.
- Removable inner camera separates from the external dive housing.
- 2" color LCD screen gives a clear live preview and menu display.
| Sensor | 14MP Panasonic CMOS |
| Lens / Field of View | 140° Wide Angle Fisheye, 14mm (35mm equivalent focal length) |
| Aperture | f/2.8 |
| Focus type | Instant fixed-focus lens, 12 in to infinity (30 cm to infinity) |
| Shutter response | 0.30 seconds |
| Shutter speed | 1/25 to 1/2000 second |
| ISO | Auto, 100 to 3200 |
| Video | 4K @ 30fps, 1080p @ 60fps |
| Shooting modes | Single, Burst (3, 7, 15, or 30 photos), Time Lapse Photo, Time Lapse Video |
| White balance | Auto, Underwater Shallow, Underwater Deep, Daylight, Cloudy, Tungsten, Fluorescent |
| LCD | 2.0" color TFT LCD, 230K resolution |
| Memory | Micro SDHC/SDXC up to 128GB (sold separately), V30 (U3) recommended for 4K |
| Battery | Removable Li-ion, 900 mAh / 3.8V / 3.42Wh |
| Battery life | 2+ hours video / 500+ still images |
| Waterproof depth | 130 ft / 40 m |
| Shockproof | 3 ft / 1 m |
| Tripod mount | Standard 1/4-20 threads |
| Weight | 7.1 oz / 202 grams (housing with inner camera and battery) |
| Dimensions (housing) | 1.9" x 4.1" x 2.6" (4.9cm x 10.5cm x 2.6cm) |
| WiFi app | Free ReefMaster app (Google Play and Apple App Store) |
⚠️ WARNING: This product contains chemicals known to the State of California to cause cancer, birth defects, or other reproductive harm. For more information, visit www.P65Warnings.ca.gov.
Frequently Asked Questions
What memory card does the ReefMaster RM-4K need?
The RM-4K uses Micro SDHC/SDXC cards up to 128GB, sold separately. SeaLife recommends a card rated Video Speed Class V30 or UHS Speed Class U3 to handle the data rate of 4K recording without dropped frames.
What is the difference between the RM-4K and the RM-4K Pro 2000 Set?
The base RM-4K (SL350) is the camera and underwater housing only. The RM-4K Pro 2000 Set (SL354) includes the identical camera and housing bundled with a Sea Dragon 2000F photo-video light, so you have a complete lighting kit out of the box.
Can the RM-4K be used with Sea Dragon lights other than the 2000F?
Yes. The housing mounts to a standard light tray and is designed to pair with Sea Dragon constant LED photo-video lights, not just the 2000F included in the Pro 2000 Set. There is no flash or external strobe sync; you simply turn the light on and adjust intensity.
How long does the RM-4K battery last?
The removable 900 mAh, 3.8V Li-ion battery provides 2+ hours of video recording or captures 500+ still images on a charge. A spare battery (SL3504) is available as an accessory for extending dive days without recharging.
















