Why Do Cruise Ships Sound Their Foghorns?

October 4, 2026

BWAAAAAAAAAH.

Two minutes later...

BWAAAAAAAAAH.

Two minutes later...

You get the idea. 😂

While cruising between Japan and Alaska, we experienced several days of particularly unpleasant weather.

Visibility became extremely poor. At times there wasn't much to see beyond a wall of grey outside the ship, and some of the outer decks were closed to passengers for safety.

And then there was the foghorn.

Every two minutes.

For hours.

Then days.

Including overnight.

If you've ever experienced this on a cruise, you might have wondered why a modern cruise ship — equipped with radar, GPS, AIS and sophisticated navigation technology — still needs to announce its presence to the ocean with an enormous horn every couple of minutes.

There's actually a very good reason.

It's not just maritime tradition. It's an international collision-prevention requirement.

Why do ships use foghorns?
Why does the foghorn sound every two minutes?
What do different foghorn patterns mean?
When are fog signals required?
Why use a foghorn when ships have radar?
What happens when fog signals aren't used?
How long have ships used fog signals?
The Empress of Ireland disaster
Why were our outer decks closed?
Can you hear a cruise ship foghorn from your cabin?

Why Do Ships Use Foghorns?

At its simplest, a foghorn tells other vessels:

We're here.

In clear conditions, vessels can visually identify one another and use navigation lights, radar, AIS and other systems to understand what's around them.

Fog changes that.

Another vessel could be relatively close but completely invisible from the bridge.

Modern ships have sophisticated electronic systems to help identify other vessels, but maritime safety doesn't rely on any single system.

A sound signal provides another independent way of alerting vessels nearby to the ship's presence.

And importantly, a horn can also be heard by smaller vessels that may not have all the sophisticated navigation equipment found on a modern cruise ship.

Cruise ship in thick fog, Skagway Alaska

Why Does the Foghorn Sound Every Two Minutes?

That very specific timing we experienced between Japan and Alaska wasn't something the captain had chosen because he particularly wanted to prevent several thousand passengers from sleeping.

It's part of the international collision regulations.

Under Rule 35 of the International Regulations for Preventing Collisions at Sea — commonly known as COLREGs — a power-driven vessel making way through the water in or near restricted visibility must sound one prolonged blast at intervals of no more than two minutes.

A prolonged blast lasts approximately four to six seconds.

So if your cruise ship is travelling through thick fog and you're hearing:

One long blast... approximately two minutes... one long blast...

that's exactly what you should be hearing.

The ship isn't doing it for atmosphere.

And unfortunately, the two-minute interval isn't optional because everyone onboard would quite like to sleep. 😂

What Do Different Foghorn Patterns Mean?

Interestingly, not every vessel in restricted visibility makes the same sound.

The pattern itself communicates information about what the vessel is doing.

A power-driven vessel making way through the water sounds one prolonged blast at intervals of no more than two minutes.

A power-driven vessel that is underway but stopped and making no way through the water sounds two prolonged blasts, with approximately two seconds between them, again at intervals of no more than two minutes.

Other vessels — including sailing vessels, fishing vessels and vessels restricted in their ability to manoeuvre — have different prescribed combinations of prolonged and short blasts.

So these aren't simply loud noises.

They're effectively a language.

A mariner hearing the signal can learn something about a vessel they may not even be able to see.

When Are Fog Signals Required?

Fog is the obvious example, which is why we generally refer to them as foghorns.

But Rule 35 isn't technically just a fog rule.

It's a restricted visibility rule.

The international regulations define restricted visibility as conditions in which visibility is restricted by:

fog
mist
falling snow
heavy rainstorms
sandstorms
other similar causes.

That means you could potentially hear the ship sounding these signals even when the conditions outside don't resemble the classic wall of white fog we normally associate with a foghorn.

The important factor is visibility, not whether the weather app happens to call it fog.

Why Use a Foghorn When Cruise Ships Have Radar?

This is probably the most obvious question.

Modern cruise ships have considerably more sophisticated navigation equipment than the vessels sailing when fog signals were first developed.

Radar can detect other vessels and objects despite poor visibility.

AIS — the Automatic Identification System — allows equipped vessels to transmit and receive information such as identity, position, course and speed.

GPS provides extremely accurate positioning.

So why are we still blasting a horn into the fog?

Because none of those systems makes the others redundant.

The COLREGs specifically account for the use of radar. A vessel detecting another vessel by radar must determine whether a risk of collision exists and take appropriate action.

But those same international regulations still require the appropriate sound signals in restricted visibility.

In other words:

Radar doesn't replace the foghorn.

The foghorn doesn't replace radar.

They're different layers of protection.

And history provides some very good examples of why relying on only one layer isn't necessarily enough.

What Happens When Fog Signals Aren't Used?

Japan's Marine Accident Inquiry Agency conducted an analysis of 91 collisions in fog involving 157 cargo ships, tankers and passenger vessels between 2001 and 2005.

Of the vessels involved:

53% had failed to sound fog signals
52% had failed to maintain a proper radar lookout
47% had failed to comply with navigation rules for restricted visibility
many had also failed to maintain a safe speed.

The findings are particularly interesting because radar is sometimes used as an argument for why audible fog signals are outdated.

Yet more than half of the vessels involved in these collisions had also failed in their use of radar.

That makes the foghorn another important means of announcing a vessel's presence when visibility is poor.

Technology is extremely good.

Humans using technology aren't always perfect.

A Collision Where the Required Signal Wasn't Being Sounded

One particularly clear example occurred in Canada in 1992, involving the passenger vessels Queen of Saanich and Royal Vancouver.

Queen of Saanich was automatically sounding its required fog signal.

Royal Vancouver entered the fog less than two minutes before the collision and had not sounded its required fog signal.

The vessels eventually saw one another, but by then they had only around 30 seconds or less before impact.

That doesn't mean sounding the horn would definitely have prevented the collision. Maritime accidents frequently involve several contributing factors.

But one of the prescribed layers of warning wasn't being used.

And that's really the point.

Maritime safety generally relies on multiple precautions working together.

How Long Have Ships Used Fog Signals?

The idea of using sound signals in poor visibility goes back much further than modern cruise ships.

International collision-prevention regulations began developing during the 19th century, as steam-powered vessels increasingly shared busy waterways with sailing ships.

Great Britain developed collision-prevention rules in 1862 and invited other maritime nations to adopt them in 1863. Within two years, 34 major maritime nations had approved and adopted them.

Sound signalling formed part of this developing international collision-prevention system.

By the late 19th century, increasingly fast steamships and changing technology meant the rules needed further development.

An international maritime conference held in Washington, DC in 1889 specifically considered more uniform marine signals, including ways of indicating vessel movements in fog, mist, falling snow and thick weather.

The system continued to evolve into today's International Regulations for Preventing Collisions at Sea, or COLREGs.

The current COLREG Convention was adopted by the International Maritime Organization in 1972, with Rule 35 establishing the sound signals used in restricted visibility today.

So when you're lying in your cruise cabin at 2am listening to:

BWAAAAAAAAAH

...you're hearing the modern descendant of a maritime safety system that's been developing for more than 160 years.

Suddenly it's almost charming.

Almost. 😂

The Empress of Ireland: When Foghorns Weren't Enough

There's another historical example that demonstrates something equally important:

A foghorn isn't a magic collision-prevention device.

In 1914, the ocean liner Empress of Ireland collided with the Norwegian collier Storstad in dense fog on Canada's St Lawrence River.

More than 1,000 people died.

But unlike examples where vessels failed to use the required sound signals, the two ships in this case were exchanging fog signals before the collision.

The official inquiry records prolonged blasts being heard and answered between the vessels after the fog obscured them.

And yet they still collided.

It's a stark reminder of why maritime safety doesn't rely on the foghorn alone.

Sound signals are one component of a much larger collision-prevention system involving:

appropriate speed
proper lookout
navigation decisions
communication
radar and other technology
correct interpretation of the situation.

A foghorn provides another layer.

It doesn't replace the others.

Why Were Our Outer Decks Closed?

The fog itself wasn't necessarily the only reason.

During periods of poor weather and restricted visibility, cruise ships may restrict passenger access to exposed outer decks when conditions include strong winds, rough seas, slippery surfaces and poor visibility.

On our voyage between Japan and Alaska, we'd already experienced days of bad weather.

With visibility extremely limited, having some of the exposed outdoor areas closed wasn't particularly surprising.

And frankly, there wasn't much sightseeing to be done anyway.

Grey.

Slightly different grey.

BWAAAAAAAAAH.

Repeat. 😂

Balconies on a cruise ship with fog above

Can You Hear a Cruise Ship Foghorn From Your Cabin?

Oh yes.

How loudly you'll hear it depends considerably on where your cabin is located.

Passengers in cabins closer to the bow or on higher decks may hear it particularly clearly, while passengers further away may experience it as more of a distant sound.

But a ship's horn is deliberately designed to be heard.

That's rather the point.

So if your cruise enters prolonged fog, particularly overnight, don't be surprised if your sleep is occasionally interrupted.

The bridge isn't doing it for atmosphere.

And unfortunately you can't ring Guest Services and ask them to turn it down. 😂

This is also one of those little things worth remembering when choosing a cruise cabin. Location can affect considerably more than simply how far you need to walk to the buffet.

Voyage Ready Read 👉 How to Choose the Best Cruise Cabin for Your Trip

The Next Time You Hear a Cruise Ship Foghorn...

It might sound old-fashioned.

It might be annoying.

And after several days of hearing it every two minutes, you may never want to hear another one again.

But that repetitive blast is actually part of an international collision-prevention system that has evolved over more than a century.

Modern cruise ships may have radar, AIS, satellite navigation and sophisticated bridge systems, but maritime safety is built around layers of protection rather than dependence on a single technology.

And sometimes one of the simplest ways of telling another vessel you're there is still:

Make a really, really loud noise.