IALACOLREG

IALA Buoyage System

The IALA Maritime Buoyage System defines fixed and floating navigation marks used worldwide. Region A (red-port) covers Europe, Africa, Australia, New Zealand, India and most of Asia; Region B (red-starboard) covers the Americas, Japan, Korea and the Philippines.

The IALA Maritime Buoyage System, in plain English

The IALA Maritime Buoyage System (MBS) is the single worldwide convention for the floating and fixed marks that tell mariners where the channel is, what to avoid, and which way is safe water. Before IALA, every country buoyed its own coast its own way — the same red can meant "keep to starboard" in one country and "keep to port" the next. After two serious collisions in the Dover Strait in 1971, IALA published a unified system in 1976 that is now used by every coastal state on earth.

There are six mark categories: lateral marks (channel edges), cardinal marks (where the danger is and which side is safe), isolated danger marks (a single obstruction with navigable water all around), safe water marks (mid-channel and landfall), special marks (cables, military zones, anchorages — not navigational), and emergency wreck marking buoys (new wrecks not yet charted). The shape, colour, topmark and light rhythm together encode the meaning — never read the colour alone.

The one thing every candidate must remember: there are two IALA regions. In Region A — Europe, Africa, India, Australasia, most of Asia — port-hand marks are red and starboard-hand marks are green. In Region B — the Americas, Japan, Korea, the Philippines — the colours are swapped: red is to starboard when returning from sea. Mix them up and you will fail every exam from the PER to the USCG Six-Pack.

Region A vs Region B — what actually changes

AspectRegion ARegion B
Port-hand mark colourRed (can shape)Green (can shape)
Starboard-hand mark colourGreen (cone shape)Red (cone shape)
Memory aid"Red right going TO sea""Red right returning from sea"
Cardinal marksIdentical — same colours, same topmarks, same lightsIdentical — same colours, same topmarks, same lights
Isolated danger / safe water / special / wreck marksIdentical worldwideIdentical worldwide
Countries (examples)UK, Spain, France, Italy, Greece, India, Australia, South AfricaUSA, Canada, Mexico, Brazil, Japan, South Korea, Philippines

Next: pick a mark category

Frequently asked questions

What is the difference between IALA Region A and Region B?
Only the lateral marks change. In Region A (Europe, Africa, Asia except Japan/Korea/Philippines, Australasia), the port-hand mark is red and the starboard-hand mark is green. In Region B (the Americas, Japan, Korea, the Philippines), the colours are swapped. Cardinal, isolated-danger, safe-water, special and emergency-wreck marks are identical worldwide.
Which IALA region covers the United States?
The United States, Canada, Mexico, Central and South America, Japan, Korea and the Philippines are all in Region B. Everywhere else — including the entire European Atlantic, Mediterranean and the whole of the Indo-Pacific west of Korea — is Region A.
What does "red right returning" mean?
It is the Region B memory aid: when you are returning from sea (entering port), the red lateral marks should be on your right (starboard). In Region A the rule inverts — red lateral marks are on your right when LEAVING port.
What do the two black spheres on a buoy mean?
Two black spheres in a vertical line is the topmark of an isolated danger mark. The body is black with one or more horizontal red bands. It marks a single danger of limited size with navigable water all around — you may pass on either side.
What is an emergency wreck marking buoy?
A blue-and-yellow vertically-striped buoy with a yellow upright cross topmark and an alternating blue/yellow light. It marks a new wreck before it can be charted; you should keep clear. After it is charted it is typically replaced by an isolated-danger mark or removed.