Why an AirTag goes silent on an ocean crossing

Because there is nobody to hear it. An AirTag has no GPS and no SIM; a location exists only when a passing iPhone relays a sighting. Mid-ocean there are no passing iPhones, so no reports are produced at all. The silence lasts the whole crossing and usually the yard time either side, and it says nothing about whether your shipment is fine.

What has to happen for a location to exist at all?

Two separate things, and both fail at sea. First, an Apple device has to come close enough to hear the tag's Bluetooth broadcast. Second, that device has to get the sighting to Apple, encrypted, so it can reach your account.

A container ship carries no crowd. The crew is small, the accommodation block is far from the stacks, and the holds are cleared and closed for the passage. Your tag is inside a carton, inside a steel container, inside a steel hull. Nothing within range is listening.

So the tag is not broken, not asleep, and not out of battery. It is broadcasting to an empty room. The Find My network is other people's phones, and the ocean is the one place with no other people.

A passenger vessel is a different case worth naming, because there the crowd exists. A ferry or a cruise ship is full of phones, and reports do happen aboard. Freight is the hard case precisely because it travels without passengers.

How long does the silence usually run?

Longer than the sea leg. People plan for the crossing and are then surprised by the quiet days at each end, which often add up to more than the voyage itself.

• A short sea crossing may be overnight, and the gap barely registers.
• A deep-sea crossing runs for days to weeks depending on the route, and produces no reports for the whole of it.
• Add the time the container sat stacked in the origin yard waiting for the vessel: steel on six sides, nobody around.
• Add the time it sits in the destination yard after discharge, and any spell in a bonded warehouse before customs clears it.
• Subtract nothing for the crossing being calm, on schedule, or well managed. None of that produces a sighting.

The practical planning number is not the sailing time. It is gate-in at the origin port to the first handling at the destination, and on a long routing that can be most of the shipment.

How dense are reports on each leg?

Why does coverage come back so sharply at the far end?

Because arriving is a human process. A box that has been untouched for two weeks is suddenly lifted by a crane operator, driven by a yard tractor driver, checked by a clerk and hooked to a truck: four people with phones in the space of an afternoon.

The first report after a crossing is therefore one of the most useful points in the whole record. It is a timestamped, independently produced marker of when your goods were physically handled at the destination, and it usually arrives before any milestone email does.

It is worth being precise about what that point proves. It dates the moment somebody came near your tag with a phone, which is shortly after the box moved, not the moment the vessel berthed. Close enough to be useful, not the same thing.

Does a silent tag mean the shipment is lost?

No. This is the single most common misreading, and it causes more worry than any real shipping problem. Silence on a sea leg is the expected outcome, and it carries no information either way.

What would be informative is a report in the wrong place: a container that shows up inland while it should be at the quay, or a tag that surfaces at a yard nowhere on the routing. That is worth a phone call. A blank fortnight is not.

The other informative case is a gap that should have ended. If the vessel has berthed, the terminal is working, and days pass with nothing, the likeliest explanation is that your box is still stacked rather than that it is missing, but that is a reasonable moment to ask the forwarder where it sits.

What can you actually do about the gap?

You cannot close it with a tag. Nothing borrows a crowd that is not there, and any product that draws a line across the ocean is drawing a guess. What you can do is make the edges of the gap as sharp and as well dated as possible.

1. Connect and start recording before packing, so the last report before the gap is a real one rather than the day you signed up.
2. Place the tag where it will report during handling: near the door end of the load, high in the stow, away from metal goods.
3. Note the last position before the silence and the first position after it. Those two timestamps bracket the whole sea leg.
4. Keep the carrier's milestones alongside the tag record. They cover the stretch your tag cannot.
5. If a guaranteed reporting interval genuinely matters, use a satellite-capable asset tracker for that shipment and accept the cost.

AirTag History polls the Find My network every 5 minutes and saves each report it gets back with a latitude, a longitude and a timestamp. It shows gaps as gaps and never interpolates across them, because a fabricated mid-ocean point would poison the only thing the record is for. Find My itself keeps nothing to look back at, because it holds one pin and overwrites it. Apple holds no readable history either, since reports are end-to-end encrypted to your Apple ID.