Best Diver Locator Systems: ENOS vs. Alternatives

While diving, surfacing far from the boat is a real and dangerous possibility. Strong currents, offshore sites, and shifting sea conditions can separate divers faster than many expect. 

This is where electronic diver locator systems become essential. 

They replace uncertainty with precise positioning and shorten the time it takes to reach a missing diver. Yet some systems are built for fast diver-to-boat recovery, while others are designed for large-scale international rescue.

This article will compare the ENOS Diver Locator System with PLBs and more to help you choose the right system based on one question that matters most. 

Do you need immediate pickup by your own boat, or escalation to global search and rescue?

What Is ENOS? (Electronic Rescue and Location System)

ENOS is a diver locator system that allows a dive boat to immediately find and recover a missing diver at sea. It is a localized system designed to support direct communication between the diver and the vessel responsible for the recovery.

ENOS is widely used by professional dive centers and liveaboards where current, drift, and offshore conditions increase the risk of separation. 

The ENOS system works as a closed loop with two main components:

1. The ENOS transmitter is a carried item by the diver that is fully waterproof. It is activated manually by twisting a large red disk, which helps prevent accidental activation underwater.

2. The ENOS receiver can be used as a portable unit or installed permanently on board. When a signal is received, the system displays the diver’s GPS position, distance, and direction relative to the vessel. At the same time, it activates a clear visual and acoustic alarm that remains active until acknowledged by the crew.

How Does ENOS Work?

ENOS works by sending a diver’s exact GPS location directly to the boat in the rare event of separation at sea. 

The ENOS process follows a simple, controlled sequence:

1. Activation: In an emergency, the diver turns on the beacon by twisting the red disk. An LED light confirms that the GPS signal is transmitting.

2. Signal Positioning: To improve transmission, the beacon should be raised as high as possible above the water and kept clear of the surface. It can also be activated underwater and sent up with an SMB.

3. Direct Transmission: Once active, the beacon sends the diver’s exact GPS coordinates directly to the boat with an operational range of up to 10 kilometers.

4. Onboard Reception: The receiver on the boat immediately picks up the signal and displays the diver’s location for the crew.

5. Recovery: The crew responds at once and heads straight to the diver for a direct pickup.

This direct diver-to-boat communication allows the crew to act without delay, without outside coordination, and without waiting for third-party rescue services. 

What are the Alternatives to ENOS?

To understand where ENOS fits, it is crucial to compare it to other available locator technologies.

1. Personal Locator Beacon (PLB)

A PLB is a personal emergency device that sends a distress signal via satellite to international rescue authorities. When activated, the signal is picked up by the International Cospas-Sarsat network and routed to a national search and rescue center, which then coordinates an official rescue operation.

PLBs offer near-global coverage, but they are not designed specifically for diving. They are intended for any situation where direct emergency communication, such as calling local authorities, is not possible. While they reliably alert search and rescue services, the response may not come immediately.

2. EPIRB (Emergency Position-Indicating Radio Beacon)

An EPIRB is an emergency beacon designed for vessels, not individual divers. It is registered to a specific boat and is built to activate automatically if the vessel capsizes or sinks, sending a distress signal via satellite.

While some EPIRBs can be manually activated, they are still intended to represent a vessel-level emergency rather than a diver-level separation. However, in situations where divers are missing from the vessel, manual activation can help alert rescue authorities that the boat is involved in an emergency. 

3. MSLD (Maritime Survivor Locating Devices)

MSLDs are short-range radio beacons designed to facilitate the rapid local recovery of persons in the water, such as offshore workers, mariners, or divers surfacing away from their vessel. Unlike long-range satellite beacons, MSLDs operate on VHF and AIS frequencies to alert nearby ships and aircraft. Modern AIS-equipped MSLDs include an integrated GPS receiver, transmitting the survivor's exact location directly to nearby digital chart plotters. 

While MSLDs are not detectable by the Cospas-Sarsat satellite network, many units can send a Digital Selective Calling (DSC) distress message directly to the Coast Guard (within a certain range). Furthermore, because they are designed for integration into life jackets, immersion suits, and dive gear, they are a primary safety tool for immediate "man-overboard" recovery.

4. Visual Signaling Tools

Visual signaling tools are the most basic and widely used safety devices in diving. These include SMBs and DSMBs, whistles, strobes, mirrors, flares, and surface dye markers that help divers attract attention once on the surface.

All visual tools rely entirely on line of sight and environmental conditions. Rough seas, low light, fog, and large swells can quickly reduce their effectiveness, even at relatively short distances.

Comparison Table

Which System Is Best for You?

The ideal choice is not to choose just one system at all, but to carry several layers of safety on board. 

Different locator systems serve different roles, and the strongest setup is one that combines fast local recovery with global emergency backup. This approach ensures you are covered whether the situation stays within your own operation or escalates beyond it.

If you are operating in remote regions or crossing open ocean, having PLBs and an EPIRB on board is essential for global emergency alerting. If you are running a dive operation as well, ENOS becomes a highly valuable addition for fast diver-to-boat recovery in current and offshore conditions. 

At the same time, visual signaling tools must always be available, as they remain the basic safety minimum on every vessel and for every diver, without exception.

Stay Ready with ENOS

For decades, NRC International has delivered professional marine and diving safety systems trusted by operators around the world. ENOS continues that legacy by giving dive boats a fast, direct way to locate and recover missing divers without relying on satellites or third-party rescue coordination.

If you want a diver rescue system that is always ready, proven in real offshore conditions, and built for immediate boat-level recovery, NRC’s ENOS is the right choice. 

Equip your vessel with ENOS and give your crew and divers the confidence that comes from knowing help is always within reach!