Travellers who want the boats unloading reserve a dawn fish auction day near Porto

What happens between 05:40 and 09:00

You are collected while it is still dark and driven out to the fishing harbour north of the river mouth. The boats have been in since about four. From the gallery above the hall you watch the crates come off, get graded by size and go under ice. The sale itself starts near six and it runs downward: the asking figure is set high and falls until somebody stops it, which is the opposite of every auction most visitors have seen. Buyers work fast because the ice is working against them. By half past seven the floor is being hosed and the last lots are loaded. You finish over coffee and bread near the harbour wall, back in the city before the shops open.

Standing on wet concrete for three hours

This is a standing day and a cold one. The hall is refrigerated, the floor is wet, and you spend most of two hours on your feet on concrete with little to lean on. Bring a coat heavier than the forecast suggests and shoes you do not mind rinsing. The smell is strong and constant; if that is a problem for you, say so before you hold a place rather than after. There are stairs down to the floor and no lift. Nobody is asked to carry anything. Anyone who wants to sit out part of the sale can wait in the cafe across the road, which is warm and two minutes away.

Inside the $148 and outside it

From $148 per person. That figure holds the pickup in the dark and the return, the gallery place for the sale, an hour with someone who explains the grading and the falling figure as it happens, and coffee and bread afterwards. It does not hold your bed the night before, anything you buy elsewhere, or a longer breakfast if you want one. It does not hold travel to or from the city, because no leg of it is carried by this office through the air or over the sea. The company running the morning invoices you in its own name; no money passes through this office, nothing about your card is seen here, and the share it earns arrives from them later.

Awkward things people ask about this day

Can we buy fish at the sale itself?

No. The sale is wholesale and only buyers registered at the hall may take a lot, so nothing on that floor can be sold to a visitor. What you can do is walk the retail market afterwards, ten minutes away, where the same catch is broken into small quantities. The guide will point out which stalls were buying an hour earlier. Nobody from this office buys on anybody's behalf.

What if the boats have not been out?

It happens, mostly between November and February, when a run of Atlantic weather keeps the fleet tied up for days at a time. The hall then holds a short sale of whatever came from further south, or none at all. You are told the evening before, and if the sale is called off entirely the day is not charged. Nobody can promise a full floor, and any page that did would be lying about the sea.

Is the 05:40 start negotiable?

No, and it is the one part of the day that nothing can be done about. The figure starts falling at first light because ice and distance decide everything here, and by half past seven the interesting part is over. Pickup is twenty to forty minutes earlier depending on where you are staying. People who want a later start are usually better served by the Wednesday market inland, which starts at eight.