If your ship is planning to pass through the Panama Canal anytime soon, be prepared to wait.

Looking at AIS data of the anchorages at both the Pacific and Atlantic ends of the canal, you will see a huge backlog of ships, mostly tankers and cargo ships it seems.

We reached out to Marine Traffic Control at the Panama Canal, who told us there were a total of 129 waiting vessels between the two anchorages as of Thursday afternoon, with waiting times right now of five days for unbooked vessels – that is vessels that did not pay the premium to reserve a space.

On Thursday, non-booked northbound vessels scheduled to pass through the canal have been waiting at anchor since Oct. 16 and 17. For non-booked southbound vessels, the wait time is even worse. Those vessels arrived on Oct. 14 and 15, seven and eight days ago.

Marine Traffic Control said the backlog is primarily due to weather conditions, including several days of fog at the canal. But we spoke with a canal insider, who said that in his decades of experience he has only seen it like this when there is some other issue going on – not one that’s weather related.

For oceangoing vessels, the goal is for 24-30 hours of what they call Canal Water Time, which includes arrival, wait time and transit, but the daily average rose to more than 37 hours in September, with a high of more than 80 hours. Transit typically should average 10 to 12 hours, so you can see that is lot of hours and sometimes days to wait.

We’re also told that booking slots, where you actually reserve a specific time and day for a fee, aren’t even available for several days out right now, so even vessels willing to pay extra need to wait several days. In fact, we’re told that there are hardly any open slots left and what is available is being auctioned off to the highest bidder for astronomical amounts – hundreds of thousands of dollars, we’re told.

Update: A statement provided to us Friday from the Panama Canal Authority said that a high level of arrivals during the last in September coincided with schedule dry-chamber maintenance. The ACP says because of the backlog, it has decided to postpone maintenance work and has assigned additional crew members to increase capacity. It has also started a temporary reduction in the number of booking slots for certain types of vessels.

AIS screenshots provided by MarineTraffic.com.