The jonline is a valuable piece of scuba diving equipment used to enhance safety, comfort, and stability during decompression stops. This versatile device enables divers to attach themselves to anchor lines or down lines and maintain their position in the water column, even in the presence of significant wave action. The jonline’s adaptability to varying thicknesses of lines and its ease of use make it a popular choice among divers of all experience levels.

History and Development

The jonline’s origins can be traced back to the early days of technical diving when divers recognized the need for a device to secure themselves to the anchor line during decompression stops. This was especially important in challenging diving environments with strong currents or heavy surface conditions. Over time, the jonline evolved into its current form, a short line with a hook device that can accommodate lines of various thicknesses.

Design and Functionality

The jonline is typically constructed from a short length of sturdy, low-stretch line or webbing, ranging from 18 to 36 inches in length. The hook device at one end of the jonline is usually made of corrosion-resistant stainless steel or other durable materials. The hook’s design allows it to fasten securely onto anchor lines, down lines, or other attachment points with ease.

On the other end of the jonline, a stainless steel or brass bolt snap is often used to attach the jonline to the diver’s harness or buoyancy control device (BCD). This ensures a strong and reliable connection between the diver and the line.

The jonline is designed to be easily adjustable, allowing divers to control their position in the water column during decompression stops. By shortening or lengthening the jonline, divers can remain at their designated stop depth while avoiding excessive strain on their bodies due to wave action or currents.

Usage and Applications

Jonline use is particularly common among technical divers, who often have longer and more complex decompression profiles due to the nature of their dives. However, recreational divers can also benefit from the added safety and comfort provided by a jonline, particularly in challenging diving conditions.

The jonline is especially useful during decompression stops in strong currents or heavy surface conditions, where maintaining a stable position in the water column can be difficult. By attaching themselves to the anchor line or down line, divers can conserve energy and focus on their decompression without struggling to maintain their position.

Additionally, the jonline can be beneficial in situations where multiple divers are performing simultaneous decompression stops on a single line. By using jonline, divers can maintain a safe distance from one another, reducing the risk of entanglement or accidental dislodging of another diver’s equipment.

Safety Considerations

While the jonline offers numerous advantages to divers, it is essential to use the device safely and responsibly. Divers should always ensure that their jonline is in good working order and free of damage or excessive wear before each dive. The hook device should be inspected for signs of corrosion, and the line or webbing should be checked for fraying, cuts, or other signs of damage.

Divers should also be aware of the potential hazards associated with using a jonline, such as entanglement or the risk of the hook accidentally disengaging from the anchor line. To minimize these risks, divers should practice using their jonline in controlled environments before employing it in more challenging conditions.

Lastly, it is crucial for divers to monitor their decompression schedules closely while using a jonline, as the device can provide a false sense of security. Divers should not rely solely on the jonline to maintain their decompression stop depths but should also remain vigilant and attentive to their depth gauges and dive computers.


The jonline is a practical and versatile piece of scuba diving equipment that

offers divers enhanced safety, comfort, and stability during decompression stops. Its simple yet effective design allows for easy attachment to anchor lines and down lines of varying thicknesses, providing divers with the ability to maintain their position in the water column, regardless of wave action or currents.

In addition to technical divers, recreational divers can also benefit from using a jonline, particularly when diving in challenging conditions where maintaining a stable position is difficult. The jonline’s adaptability and ease of use make it an essential addition to any diver’s equipment arsenal.

However, as with any piece of diving equipment, it is crucial to use the jonline responsibly and to be aware of potential risks associated with its use. By regularly inspecting the jonline for damage, practicing its use in controlled environments, and remaining vigilant about decompression schedules, divers can ensure that the jonline serves as a valuable asset in promoting safe and enjoyable diving experiences.

With the continued growth and development of the scuba diving industry, the jonline remains a testament to the importance of innovation and adaptation in the pursuit of safer and more enjoyable underwater experiences. As diving technology continues to evolve, the jonline will likely remain a staple piece of equipment for divers worldwide, providing much-needed stability and security during decompression stops in diverse and challenging underwater environments.

In summary, the jonline is an essential and versatile piece of scuba diving equipment that provides numerous benefits to divers, from improved safety during decompression stops to increased comfort in challenging diving conditions. By using the jonline correctly and responsibly, divers can enhance their underwater experiences, ensuring that they can safely and comfortably explore the underwater world for years to come.