Reading Great Lakes and St. Lawrence Seaway ship traffic

A connected waterway is not a single live schedule

A ship-tracking map helps show the relationship between lakes, channels and ports, but a position report does not describe an entire transit. The Seaway's locks and channels overview explains the infrastructure linking different parts of the system. Use that geographic context to identify which section you are discussing. Avoid applying a condition reported for one lock or channel to the whole Great Lakes region. An interesting vessel marker is the beginning of a question about its journey, not proof of its next movement.

Official Seaway AIS has an operational role

The Seaway's AIS explanation describes integration with its traffic management system. It also describes operational information such as water conditions and lock availability, beyond vessel positions alone. Those capabilities belong to the official system described by the source. They are not features automatically inherited by any website displaying AIS markers. PocketWorld does not provide the Seaway's lockage order, traffic-management instructions or a complete operational picture.

Check the season and the affected section

Seaway Notices are organized around issues affecting a navigation season, with both system-wide and regional material. The separate opening and closing information provides a starting point for current seasonal information. Verify the year and relevant section rather than reusing a date from an old search result. This guide intentionally does not publish fixed opening dates, current restrictions or a claim that the system is open today. Those facts need the current official notices and any subsequent revisions.

Do not infer a lock queue from a screenshot

Several visible vessels near a channel do not, by themselves, reveal their sequence, reason for stopping or next lock time. Check the age and source of each report before even comparing their locations. A marker with an old timestamp should not be grouped uncritically with newer observations. Nor does multiplying distance by a recent speed produce a reliable transit schedule: the calculation says nothing about the steps between those points. If your question requires an expected lock passage or an official movement update, use the relevant operator information rather than assigning times from the map.

A useful research workflow on either side of the border

First identify the lake, channel or port in question. Then inspect available vessel reports in PocketWorld and retain each observation time. Use the official infrastructure overview to understand the section, and current notices for published operational context. Keep missing reports explicitly marked as unavailable instead of interpreting them as an absence of traffic. Both the US and Canadian country collections link to this single guide because the waterway is shared; it is not duplicated into competing country versions. The result is a source-linked educational overview, not a navigation chart, lock reservation service or guaranteed arrival forecast.