Ocean Reef GSM Mercury
Ocean Reef GSM Mercury is backordered and will ship as soon as it is back in stock.
Pickup currently unavailable at In Store
Ocean Reef integrated dive mask sizing. Imperial in bold, metric underneath.
| Size | Nose bridge to chin in · cm |
|---|---|
| S/M |
3.9–4.5 10–11.5 |
| M/L |
>4.5 >11.5 |
How Ocean Reef measures
It is essential to choose a suitable size. You can choose between size S/M (for adults with smaller faces, women and children over 12 years old) and size M/L (for an adult male, or larger faces).
- Nose bridge to chin: Measure the distance between the bridge at the top of your nose and the bottom of your chin.
- Try-on: There are two different size categories on the chart: Small/Medium and Medium/Large. If the measurements fall within the both ranges, then the diver should technically be able to wear either full face mask (M/L or S/M), and in that case should try on a mask to select the best fit. Once the mask is tight on your face, if there is NO SPACE between your chin and the silicone skirt of the mask, you've got the right size.
Source: Ocean Reef’s size chart (original chart). Values in the second unit come from Ocean Reef’s own chart where it prints them.
Ocean Reef GSM Mercury is backordered and will ship as soon as it is back in stock.
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Product Information
Ocean Reef GSM Mercury is a wireless ultrasonic communication unit giving divers dual-channel voice contact with a range up to about 800 ft (250 m). It is built for scuba divers, dive professionals, public safety teams and training groups who need reliable diver-to-diver or diver-to-surface communication without a cable.
Who it is for
The GSM Mercury suits recreational divers who want to stay in voice contact with a buddy across a dive site, instructors running guided groups, and professional or public safety teams that need reliable voice contact, with hands-free communication available through DAT mode. Because it mounts through the mask's Extender Frame, it is built around Ocean Reef's own full-face masks such as the Neptune series, and it can also be adapted to several other full-face mask brands.
Key details
- Dual channel operation (ch1 and ch2) with ultrasonic transmission around 31.768 kHz, push-to-talk to transmit and continuous receive.
- Two speakers with 3-level volume adjustment and a D-Mic microphone with a hydrophobic membrane to reduce exhalation bubble noise.
- Rechargeable/replaceable battery rated for approximately 25 to 30 hours of use per charge, about 1 hour to recharge.
- Automatic activation on submersion, voice menu prompts, and DAT mode for hands-free transmission.
- Folds into the mask for compact storage and travel.
Compatibility and sizing
The GSM Mercury is compatible with all Ocean Reef integrated dive masks and is optimized for the Space and Neptune series through the NACS mounting interface. With the correct Ocean Reef adapter, it can also mount to OTS masks, Interspiro AGA masks and Kirby Morgan M-48 MOD-1 masks. It hardwires to ALPHA PRO X DIVERS units through a 6-pin waterproof connector and is VHF interface-ready, and it communicates wirelessly with any other Ocean Reef unit, or a competitor's unit, set to the same channel.
DiveCatalog.com is an authorized Ocean Reef dealer and a dive shop in Irvine, California, open since 2003. Call 888-701-4017 or start a chat if you need help matching the GSM Mercury to your mask or confirming channel compatibility with another diver's unit.
- Wireless ultrasonic communication with a range of up to about 800 ft (250 m) between units.
- Dual channel operation (ch1 and ch2) for separate teams or conversations.
- Two speakers with 3-level volume adjustment for a clear, stereo-like listening experience.
- PTT/MIC assembly with an ergonomic push-to-talk button and lever for easy transmit control.
- D-Mic microphone with a hydrophobic membrane that reduces exhalation bubble noise.
- Replaceable battery with approximately 25 to 30 hours of autonomy, as listed by Ocean Reef.
- Automatic activation when submerged, with voice menu prompts for straightforward operation.
- Foldable into the mask for compact storage and transport.
- Hands-free DAT mode (Digital Activation Transmission) allows hands-free communication without holding the push-to-talk button.
- Cross-compatible with all Ocean Reef wireless units and competitor units on the same channel.
- 6-pin waterproof connector for hardwire connection to ALPHA PRO X DIVERS units; VHF interface-ready.
| SKU | OR033150 |
| UPC | 764500011507 |
| Brand | Ocean Reef |
| Product type | Wireless ultrasonic dive communication unit |
| Channels | Dual channel (ch1 and ch2) |
| Wireless frequency | Ultrasonic, channel 1 at approximately 31.768 kHz; push-to-talk to transmit, continuous receive |
| Range | Up to approximately 800 ft (250 m) between units |
| Battery | User-replaceable. Manufacturer pages conflict: 9V alkaline only versus rechargeable with 25 to 30 hours of autonomy and about 1 hour charge time. Confirm with Ocean Reef before publishing. |
| Microphone | D-Mic with hydrophobic membrane |
| Volume control | 3-level adjustable, two speakers |
| Mounting | Compatible with all Ocean Reef IDMs; optimized for Space/Neptune masks via NACS |
| Connectivity | 6-pin waterproof connector for hardwire to ALPHA PRO X DIVERS; VHF interface-ready |
| Dimensions | 9.00 in W x 6.50 in H x 2.50 in D (22.86 cm x 16.52 cm x 6.40 cm) |
| Warranty | 2 years |
| Compatibility | Ocean Reef full face masks with Extender Frame; OTS, Interspiro AGA, and Kirby Morgan M-48 MOD-1 masks with the proper Ocean Reef adapter |
⚠️ 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
How does the Ocean Reef GSM Mercury underwater communication unit work?
The GSM Mercury is a digital wireless underwater voice communicator that mounts to an Ocean Reef full-face mask like the Neptune III (via the mask's Extender Frame). It uses push-to-talk to transmit and receives continuously, with two speakers at three volume levels and a hydrophobic microphone. Range is up to about 250 meters (800 feet), the unit is rated to 40 meters, and the rechargeable battery gives about 25 hours of use per charge via micro-USB.
What is the difference between the GSM Mercury and the GSM Mercury Dual Power?
They are the same communication unit with different channel setups. The standard GSM Mercury has two fixed frequency channels. The Dual Power version instead runs a single channel with two selectable power levels — normal power for full range, and a reduced-power mode intended for close-range use like training groups — and is identified by its Dual Power label. Both mount to and are optimized for Ocean Reef Neptune-series full-face masks.
How far can you talk underwater with the Ocean Reef GSM Mercury?
The GSM Mercury has a range of up to about 250 meters, roughly 800 feet, between units. That is far beyond normal buddy spacing, so in practice it covers a whole team on a typical dive site. Both divers need a unit set to the same channel for the link to work.
How deep is the Ocean Reef GSM Mercury rated to?
The GSM Mercury unit is rated to 40 meters, which covers the full recreational range. That matches the working depth of the Ocean Reef full-face masks it mounts to, so the comms unit is not the limiting piece of the system for recreational diving.
How long does the Ocean Reef GSM Mercury battery last?
The rechargeable battery gives about 25 hours of use per charge, recharged over micro-USB. That is several days of diving between charges for most people, so you are not scrambling for power on a liveaboard.
Do I need a full-face mask to use the Ocean Reef GSM Mercury?
Yes. The GSM Mercury mounts to an Ocean Reef full-face mask such as the Neptune III, using the mask's Extender Frame, and it is optimised for the Neptune-series masks. There is no standard-mask version, so budget for the mask, the extender frame, and the comms unit as one system.
Is the Ocean Reef GSM Mercury hands-free?
Partly. Receiving is continuous, so you always hear other divers without doing anything, but transmitting uses push-to-talk, so you press to speak. The unit has two speakers with three volume levels and a hydrophobic microphone, which is what keeps speech intelligible through water.
Do both divers need an Ocean Reef GSM Mercury to talk?
Yes. Underwater voice comms are unit to unit, so every diver in the conversation needs their own GSM Mercury on a matching channel. The standard GSM Mercury has two fixed frequency channels; the Dual Power version runs a single channel with a full-power and a reduced-power setting, so mixing versions in one group needs planning before you get in the water.
Can the Ocean Reef GSM Mercury work with masks other than Ocean Reef models?
Yes, with the proper adapter. Ocean Reef publishes adapter sets for OTS masks, Interspiro AGA masks and Kirby Morgan M-48 MOD-1 masks, so divers using those full-face masks can still run the GSM Mercury. Without an adapter, it mounts directly to Ocean Reef masks through the Extender Frame and NACS interface on Space and Neptune series masks.
What warranty does the Ocean Reef GSM Mercury come with?
The GSM Mercury carries a 2-year manufacturer's warranty. Ocean Reef also advises rinsing with fresh water after dives and avoiding solvents and direct sunlight.
Can the GSM Mercury hardwire to another dive communication system?
Yes. It has a 6-pin waterproof connector that allows a hardwire connection to ALPHA PRO X DIVERS units, and it is VHF interface-ready for integration with surface communication setups. This is separate from its normal wireless ultrasonic link, which works with any other Ocean Reef or compatible competitor unit on the same channel.
How do I care for the Ocean Reef GSM Mercury after a dive?
Rinse it with fresh water after every dive and let it dry away from direct sunlight. Avoid solvents or harsh cleaners on the housing, speakers or microphone, since the unit is designed for immersion but its electronics and hydrophobic D-Mic membrane can be damaged by chemical exposure.


















