START WITH A QUESTION
Can an inflatable drift away even when the waves look small?
LOOK CLOSELYLook separately at the air arrows and water arrows. Wind acts on the part of an object above the water too.
Wind: moving air
Wind acts on bodies and equipment exposed above water.
Waves: a travelling disturbance
Wave direction is not necessarily the direction of drift.
Currents: moving water
Water moves in currents, including rip and tidal currents.
This content has not yet been reviewed by a safety specialist. Follow current official information and instructions at the site.
Three related but different movements
NOTICE THISAre moving air and moving water the same thing?
WHAT THIS TELLS USWind, waves and currents are different. A drifting object can be affected by more than one.
The appearance of waves cannot tell you how something will drift.
Wind is moving air. Waves carry a disturbance through water. A current is the movement of the water itself. They interact, but they are different phenomena.
A floating person or object is affected by wind on the parts above water, as well as by currents and waves. Wind direction alone cannot predict the object’s actual route or speed.
Go deeper: is all offshore drifting a rip current?
A rip current is water flowing away from the nearshore area. An offshore wind can also push an inflatable away from land. Moving offshore does not, by itself, identify the cause. Think separately about air and water movement.
Go deeper: one arrow cannot predict a journey
Objects differ in the shapes exposed to air and submerged in water. The same wind does not guarantee the same motion for every floating object. This diagram separates influences; it does not calculate an arrival place or time.
Wind from land can push inflatables out
NOTICE THISWhat can happen when wind blows from land towards the sea?
Offshore: land to sea
Wind can push an inflatable away from shore.
Onshore: sea to land
Waves, currents and coastal terrain can still pose hazards.
WHAT THIS TELLS USWind can carry an inflatable away from the shore.
Being close to shore does not remove the effect of wind.
Here, offshore wind means wind blowing from land towards the sea. Swim rings and other inflatables can be affected by it, especially tall or bulky toys with a large area exposed to the wind.
The Japan Coast Guard advises keeping hold of an inflatable carrying a child and avoiding its use in strong wind. A swim ring is not a substitute for a correctly fitted life jacket. Check the site’s equipment rules too.
Go deeper: is wind towards land safe?
An onshore wind does not remove hazards from waves, currents or terrain. Neither ‘onshore’ nor ‘light wind’ is permission to swim.
Sources for this explanation: G1
A north wind comes from the north
NOTICE THISIf wind speed is given as one number, is the wind always that strong?
Wind can be above or below its average
Sea to the north
From sea in the north to land in the south: onshore here.
Sea to the south
From land in the north to sea in the south: offshore here.
WHAT THIS TELLS USWind strength varies. An average and a short gust describe different things.
Read the wind direction, then look at which way the coast faces.
Weather reports name wind direction by where it comes from. A north wind moves air from north to south. Its relationship to the shore is reversed when the sea lies north of the land instead of south of it.
The diagrams compare directions only. Headlands, bays and nearby terrain also affect local wind. Check the place and time a forecast or observation refers to, and follow local guidance.
Go deeper: average wind and gusts
JMA normally reports wind speed as a 10-minute average; instantaneous wind speed is a 3-second average. Wind varies during that time. An average is not a constant speed you can expect at every moment.
Go deeper: do not mix up the measurements
JMA wind speed uses a 10-minute average; instantaneous wind speed uses a 3-second average. Maximum wind speed and maximum instantaneous wind speed are therefore different measures. A low average does not mean the wind stayed weak throughout. This diagram provides no threshold for deciding whether swimming is safe.
Sources for this explanation: G2
Check, observe and change your plans
NOTICE THISAre the checks finished once you leave home?
WHAT THIS TELLS USKeep checking conditions and local instructions after you arrive.
One wind-speed number cannot decide whether to enter the sea.
Before leaving, check current wind, wave and warning information for your destination and visiting hours. Swell can arrive from far away, so do not judge conditions from a sunny sky or light local wind alone.
On arrival, check whether swimming is permitted, read signs and listen to lifeguards. Agree to stop if the sea or someone’s condition changes. This lesson does not replace practical swimming or rescue instruction, or training for activities such as stand-up paddleboarding.
CONNECT THE PICTURE AND THE WORD
Words to remember
- Wind direction
- The direction wind comes from. A north wind comes from the north.
- Offshore wind
- Wind blowing from land towards the sea.
- Drift
- Movement under the influence of wind, moving water and other forces.
CAN YOU EXPLAIN IT IN YOUR OWN WORDS?
Check your understanding
Think first, then open each question to read the explanation. You can look back at the diagrams.
Q1Does a north wind blow towards the north?
Explanation: No. It blows from the north. Check the map separately to see where the sea lies.
Q2If two days have the same average wind speed, must their gusts be the same?
Explanation: No. Different patterns of stronger and weaker wind can have the same average.
LET’S THINK
A question to explore further
The forecast says ‘north wind’. At a coast with the sea to the south, does that wind blow towards land or away from it? Is that enough to decide whether you can swim?
Show a hint and explanation
On this simple map, it blows from land in the north towards sea in the south: offshore. Real wind is also affected by terrain. Either way, wind direction alone cannot establish whether swimming is permitted or safe. Check waves, currents, official updates and local instructions.
Explore together, at home or in class
Place a north-to-south arrow over a map, then swap the sea and land. Explain that the arrow shows air movement, not the path a person or inflatable will follow.
Sources & further reading
We developed our own explanations, diagrams and learning questions using these sources. Inclusion does not imply review or endorsement by the source organisation. Links marked “Japanese” lead to Japanese-language material.
Sources for the added diagrams and explanations
Additional sources checked: 2026-09-21. Numerical diagrams use invented teaching values.
- [G1] Japan Coast Guard: inflatable beach toys (Japanese) ↗Wind acting on inflatables and the risk of drift.
- [G2] JMA: wind terminology (Japanese) ↗Wind direction, average and instantaneous speed, and wind pressure.
Original lesson sources
- [1] Japan Coast Guard: using inflatables (Japanese) ↗Wind exposure, supervision, wearing equipment and conditions of use.
- [2] Japan Coast Guard: precautions at sea (Japanese) ↗Offshore winds, rip currents, equipment and local checks.
- [3] JMA: understanding waves (Japanese) ↗Wind waves, swell and waves arriving where local wind is light.
- [4] JMA: wind terminology (Japanese) ↗Direction, average and instantaneous speed, and terrain.
- [5] JMA: wind questions and answers (Japanese) ↗Interpreting observations and variation over time.
First published: 2026-09-20 · Updated: 2026-09-21 · Original sources checked: 2026-09-20 · Editorial policy