Communicating at the surface and at night

In short

At the surface, the team must be able to tell the boat that all is well or that it needs help, sometimes from far away and in waves. At night, underwater, signals are made with a light or lit up. Whistle, horn, surface marker buoy, mirror and strobe help you be spotted. These codes are reviewed at the briefing, especially for a night dive, a drift dive or a dive far from the boat.

Why it matters

From a boat, a diver's head in the waves is hard to see, and an ambiguous gesture can trigger an unnecessary rescue or, worse, let a real emergency go unnoticed. At night, a team that can no longer see each other gets separated very quickly. Clear signals, known by all and prepared in advance, shorten the surface team's reaction time.

Surface signals to the boat

• All is well: one hand on top of the head, the arm forming an arc, or both arms forming a circle above the head. This gesture can be seen from far away.
• Need assistance, not urgent: an outstretched arm, or a signal agreed at the briefing, to ask the boat to pick up the team.
• Distress: an outstretched arm waving up and down repeatedly, possibly slapping the water, or fins waved out of the water. Add the whistle or horn.

At the surface, inflate your BCD to float without effort and stay together: a tight group is easier to see than scattered divers.

Light signals at night

• All is well: a circle drawn with the light beam, on the bottom or in front of you. Answer with the same circle.
• Attention / problem: a quick sweep from side to side, or up and down, to get attention. The buddy then joins the diver who is signalling.
• Hand signals: light up your own hand with your light, without aiming at the other diver's face.
• Never dazzle: shining a beam into someone's eyes blinds them for several seconds. Point the light down or to the side when you approach.
• Light off or failed: move close to your buddy immediately and use your backup light.

Sound signals

• Whistle: at the surface, a few short, repeated blasts attract attention and carry far.
• Horn connected to the low-pressure hose: more powerful, to be used only at the surface.
• Tapping on the cylinder: underwater, tapping the cylinder with a hard object (karabiner, back of a line cutter) or using a dedicated rattle gets your buddy's or guide's attention.

Being spotted by the boat

• Surface marker buoy inflated at the surface: a buoy deployed and held upright can be seen from far away, by day and by night if lit.
• Signalling mirror: in sunny weather, aim the reflection at the boat.
• Strobe: at night, a strobe attached high up, or the primary light pointed at the boat, lets you be spotted.
• Stay together and calm: save your energy and do not swim against the current to reach the boat; the boat will come to you.

Organising communication at the briefing

The briefing specifies:

• the surface signals used by this boat or dive centre;
• the light signals for a night dive;
• what to do if the team gets separated: usually, look around briefly (at night, cover your light against your body to spot the glow of the others), then ascend safely and meet at the surface;
• who carries a surface marker buoy, a strobe, a whistle;
• the planned exit point and what to do if you surface elsewhere.

If you are unsure about a code, ask before entering the water.

Key takeaways

• At the surface: hand on head for "all is well", waving arm for distress.
• At night: light circle for "OK", sweep to get attention, never in the eyes.
• Whistle and horn at the surface, tapping the cylinder underwater.
• Surface marker buoy, mirror and strobe to be seen; stay together.
• Codes are reviewed at the briefing.

Further reading

The diving hand signals guide presents underwater signals; the safety accessories guide describes signalling equipment; the specialty dives guide covers night diving.