Floats, Flags, Buoys

What every diver needs to know about floats, flags and buoys

Frequently asked questions

Can I attach the dive flag directly to my BCD or SMB?

The dive flag must be displayed on a float at the surface throughout the dive — it cannot be carried by the diver. It needs to be visible above the waterline so boat traffic can see it from a distance. A float anchored with a weight keeps the flag stable even in moderate current or chop. The SMB you deploy at the end of a dive is separate from the dive flag — the SMB signals your ascent position to the boat, while the dive flag marks the dive area throughout the dive. In Canadian waters where both are relevant, you need both a flag and float at the surface and an SMB in your pocket for ascent.

What is a DSMB and how is it different from a standard SMB?

A DSMB (Delayed Surface Marker Buoy) is an SMB that is deployed while the diver is still underwater, signalling ascent position before reaching the surface. All SMBs used for end-of-dive signalling are technically DSMBs. The term is sometimes used specifically for open-bottom models that are inflated by directing a breath from a regulator second stage into the tube from the bottom opening — this allows faster inflation at depth than an oral inflator, and is preferred by technical divers deploying during decompression stops. The closed-bottom model with oral inflator (the 45-inch SMB) is an oral-inflate DSMB — a small amount of air is exhaled into the inflator to partially fill the tube, which then expands as it ascends. Both styles serve the same core function; the bottom-inflate model is faster to deploy at depth.

How do I use a reef hook safely without damaging the reef?

A reef hook should only ever be placed on bare rock, coral rubble, or sand — never on living coral, sea fans, or any biological structure. Before hooking in, identify a solid, non-living attachment point. Hook in gently and confirm the point holds before letting the current take your weight. Keep your body horizontal and streamlined — if your fins are hanging below you, you may be disturbing the bottom with your fin wash. Unclip and re-stow the hook before ascending. In most locations, reef hook use is taught as part of advanced diving in currents — if you have not been shown the technique by an Instructor in the actual conditions, practice the clip-in and clip-out procedure in controlled conditions first.