Signal Tube
Definition
A signal tube, also called a surface marker buoy (SMB), is an inflatable device used to signal a diver’s location at the surface.
More on Signal Tube
A signal tube is typically deployed at the surface to make divers more visible to boats and shore observers. It's often brightly colored (orange, yellow, or pink) and stands upright when inflated. Unlike a DSMB, which is deployed underwater during ascent, a signal tube is used on the surface after a diver has surfaced. It's crucial for drift dives or surf entries, where divers may be far from the entry point. Carrying one improves safety and aids in faster recovery by boat crews.
Frequently Asked Questions
A signal tube is deployed at the surface, while a DSMB is released from underwater. Both increase diver visibility.
Use it after surfacing during drift dives, strong currents, or when surfacing far from the boat.
Use your regulator or orally inflate through a valve. Most tubes will stand vertically when fully inflated.
Some agencies recommend or require it for open water dives. It’s especially important when diving from boats.
Yes, many come with a reflective strip or attachment for a strobe or glow stick.