Three levels of container tracking
1. Container number in the carrier's system
Every container has a number (e.g. MSCU1234567), and every shipment a bill of lading (B/L) number. The carrier's website shows events for them: gate-in, loading on the vessel, discharge, gate-out. This is not a position on a map. Events appear with a delay, and between ports nothing changes for days. After gate-out – on the road or rail leg, where most theft happens – information usually stops.
2. Carrier smart containers
More and more carriers fit IoT devices to their own containers. Reefers are furthest ahead: according to the CEO of DCSA, Maersk has equipped almost all of its reefers and MSC about a quarter of a million. In 2024 Hapag-Lloyd was the first to launch tracking of standard dry containers and has fitted devices to more than two thirds of that fleet. DCSA stresses, however, that adoption is uneven and that different carriers' systems do not always talk to each other.
From the shipper's point of view there are limits: data access depends on the carrier, every carrier has a different portal, and devices in dry containers mainly use cellular networks, which – as ABI Research notes – work well inland but less so at sea.
3. Your own tracker on the container
Your own device gives a view that is independent of the carrier: one platform for all carriers, positions on the road and rail legs too and, above all, alarms – door opening, cut seal cable, device removal, geofence entry or exit.
Does GPS work in the middle of the ocean?
A GPS receiver works everywhere; the problem is sending the position. Cellular devices (4G, LTE-M) transmit within network coverage: in port, near the coast, on land. If you need positions and alarms during the voyage as well, choose a device with satellite connectivity, such as the AT10G seal with Iridium and 4G, which works anywhere on Earth.
Why it matters
- Losses at sea happen. According to the World Shipping Council, 1,478 containers were lost at sea in 2025 – more than twice as many as a year earlier (576). That is a tiny share of the roughly 280 million containers carried, but for a cargo owner what counts is their own container.
- Theft and smuggling happen on land. Stops are the most exposed: terminal, yard, parking area, consignee's warehouse. That is where your own tracker with a door-opening alarm gives you time to react.
- Disputes and claims. The history of positions and events shows where and when the container was opened or hit.
Which device to choose
- Quick magnetic mounting – AT410 (4G, IP66) reports position, door opening and removal attempts.
- Cargo condition – Tetis, mounted on the door hinge, alarms on opening and measures temperature, humidity, light and shocks.
- Seal and tracker in one – the solar AT10K or SolarGuardX 110 locks the doors and alarms on every opening attempt, while the solar panel extends operation on long routes.
- Voyages without coverage – AT10G with Iridium satellite connectivity.
For a full overview see cargo container monitoring. Before buying more devices, you can test them on your own route with the starter kit. See also how an electronic seal differs from a mechanical one.