Open Box Underwater Signaling — Being Seen and Being Found

Getting separated from the boat is one of the more genuinely dangerous things that happens in recreational diving, and it usually isn't dramatic — a current runs stronger than expected, a surfacing point drifts a few hundred metres, and suddenly a diver's head is one small dark object in a large amount of moving water. Signaling equipment is what closes that gap.

This collection covers surface marker buoys, DSMBs, whistles, and audible and visual signaling devices. Every item is inspected and graded before listing; see Product Conditions for full definitions.

Visual Signaling

A surface marker buoy is the primary tool. Deployed from depth on a spool, it tells the boat where you are before you surface — which matters most during a safety stop, when you're stationary and drifting. Deployed at the surface, a tall buoy makes you visible over chop that would otherwise hide you completely.

Length matters more than most divers expect. A 1m marker disappears behind waves; a 1.8m marker stays visible in conditions where a shorter one doesn't. Bright orange and yellow are standard, and some markers include reflective tape for low light and searchlight visibility.

Audible Signaling

Sound travels further than sight at the surface and works when you're behind a swell. A simple whistle attached to your BCD inflator costs almost nothing and works without power. Air horns powered from the low-pressure inflator are considerably louder and carry over engine noise, which a whistle often can't.

Practise Deployment Before You Need It

Deploying an SMB from depth involves managing a spool, inflating the marker, and avoiding getting line wrapped around yourself while maintaining buoyancy — all at once. It goes wrong the first few times. Practise it in shallow water or a pool rather than learning during an actual drift.

Why Buy Open Box Signaling Gear from DiveCatalog.com?

• Inspected and graded — condition stated clearly on every listing
• Expert advice — our team can help you choose marker length and deployment method
• Fast shipping — in-stock items ship within one business day
• 30-day returns — with RMA approval; see our Returns & Exchanges page
• Rewards program — earn points on every purchase

Frequently Asked Questions

What length SMB should I buy?

Longer is more visible. A 1.8m marker stands well clear of chop; shorter markers disappear behind waves in anything but flat conditions. For drift diving or anywhere with surface swell, buy the taller option.

What is the difference between open and closed circuit SMBs?

An open-bottom SMB is filled from a regulator and can spill gas if it tips. A closed-circuit SMB has a valve that traps the gas inside, so it stays fully inflated regardless of orientation — more reliable for maintaining a visible profile in rough water.

Should I carry both a visual and audible signal?

Yes. They work in different situations — a marker is visible at distance in daylight, while sound carries when you're behind a swell or the boat isn't looking your way. Both are small and light enough that there's no real reason to choose.

Do open box items come with a warranty?

No. Open box and used products are not eligible for manufacturer warranty coverage. Inspect any used marker for pinholes and seam integrity before relying on it.

Browse the full collection above, or see all Open Box & Used gear.