No snorkelling
Snorkelling is prohibited.
Understanding this sign
Red circular signs with a diagonal bar identify an action that must not be taken in the marked area.
Check what object or action the symbol prohibits. A prohibition sign does not identify all the hazards in an area.
Meaning of ISO 7010 P050
P050 prohibits the use of snorkelling equipment — mask, snorkel, and fins — in the signed area. The registered ISO function is specific about equipment rather than swimming generally: a site displaying P050 alone is restricting face-down surface swimming with a breathing tube, not necessarily all bathing. The pictogram shows a masked, snorkel-equipped head at the waterline under the red prohibition roundel.
Like the rest of the aquatic prohibition series, P050 originated with the ISO 20712-1 water safety signs before being incorporated into the ISO 7010 register. It is aimed at beaches, marinas, marine parks, and pools rather than industrial premises, and it is often accompanied by text or a map defining exactly which stretch of water the ban covers.
Why Snorkelling Gets Banned Where Swimming Doesn't
A snorkeller presents a uniquely poor profile to boat traffic: face down, moving slowly, with only a tube and the back of a head above the surface, and unable to hear an approaching engine well. Harbour authorities and marina operators therefore ban snorkelling in navigation channels, boat lanes, jet-ski corridors, and slipway approaches even where ordinary swimming is tolerated nearby, because a swimmer at least keeps their head up and can react.
Conservation and infrastructure drive the other bans. Marine protected areas restrict snorkelling over fragile reef, seagrass, or spawning grounds to prevent trampling and disturbance; aquaculture operators keep people away from nets and lines; and water companies exclude snorkellers from intake and outfall structures where surface currents can pull a slow-moving person toward screens.
P050 Alongside P049 and P051
The three signs form a ladder of restriction. P049 closes the water to everyone; P050 removes snorkelling equipment while potentially leaving plain swimming open; P051 targets sub-aqua breathing apparatus and the depth exposure that comes with it. A marine reserve might permit swimming at the surface, ban snorkelling over a sensitive reef flat, and ban scuba everywhere — three different signs telling three different stories.
For sign specifiers the practical rule is to match the sign to the enforceable rule. If lifeguards or wardens will stop anyone in the water, post P049. If the concern is specifically masks and snorkels near boat traffic or protected habitat, P050 says exactly that, and pairing it with a boundary map or buoy line prevents arguments about where the restriction ends.
Where you will see P050
Harbour authorities and marina operators post it across navigation channels, boat lanes, jet-ski corridors, and slipway approaches, where a snorkeller is nearly invisible to boat traffic. Marine protected areas use it over fragile reef, seagrass, and spawning grounds, and water companies exclude snorkellers from intake and outfall structures, usually with a map or buoy line defining the boundary.
Common questions about P050
Does a no snorkelling sign mean I can't swim there at all?
Not necessarily. P050's registered function is to prohibit the use of snorkelling equipment, so on its own it restricts snorkelling rather than all bathing. Many sites, however, post it together with P049 (no swimming) or local bylaw text that widens the restriction. Read the full sign panel and any flags before entering the water, and treat the strictest posted message as the rule.
Why is snorkelling banned in harbours and marinas?
Because snorkellers are nearly invisible to vessels. A person swimming face down shows only a snorkel tip and the crown of the head above the water, moves slowly, and hears engines poorly. In channels, berths, and slipway approaches, propeller strike risk is high enough that authorities prohibit snorkelling outright, usually with P050 posted at quaysides, pontoons, and launch points.
What is the difference between ISO P050 and P051?
P050 prohibits snorkelling equipment — surface swimming with mask, snorkel, and fins. P051 prohibits sub-aqua (scuba) equipment, meaning underwater diving with a breathing apparatus. A site can ban one and not the other: marine reserves sometimes allow guided snorkelling while banning scuba, and busy boat channels typically ban both. Check which pictogram is shown; the P051 figure carries tanks.
Reference details
| Symbol code | P050 |
|---|---|
| Sign family | ISO Prohibition Signs |
| Standard reference | ISO 7010:2019 / ISO 3864-1 ISO Online Browsing Platform: P050 |
| Screen color reference | #FF0000. Screen colors are not a production color specification. |
| Download formats | SVG reference artwork; a 1024 × 1024 pixel PNG conversion on a white canvas. |
| Record date | · How to interpret our dates |
| Page updated |
Choosing a physical sign size
Download dimensions are not installation dimensions. Select sign size, material, placement, and lighting using the applicable standard and the actual viewing conditions. Chemical label sizing follows its own rules. Read the artwork and sizing guide.
Sources and artwork credits
- Artwork source
- Wikimedia Commons file page
- Creator credited by source
- ISO
- License
- Public domain
- Source metadata checked
SVG files are local reference copies. PNG files are raster conversions. Check the linked file history and license terms before reuse; a source-metadata check is not certification of the artwork or a workplace installation.
Report a correction to this reference
