On the way to Hamburg visit the remnants of the shipwreck of a Finnish four-masted schooner-cum-motor glider at Hamburg Harbor.
The ship carried wood and caught fire on October 20, 1926. Eventually, it was towed to and abandoned at Blankenese Beach, where it is still sticking out of the water, and you can see it!
Have a walk at the beach and see this piece of history.

The Museum of Hamburg History is a beautiful place worth visiting. It displays Hamburg's life, culture, and urban development. But there is one special thing you should come here for - a pirate's skull! In 1878 it was accidentally found and was brought to the Hamburg Museum.
They say the skull belonged to the infamous 14th-century pirate Klaus Störtebeker. But nobody knows. Legend says that Störtebeker and his men were captured and brought to trial in 1401, and sentenced to execution. Störtebeker proposed that he be the first to be beheaded, and they should let go of other men who he will pass by as a beheaded body. It is believed that his headless body walked past eleven of his men. However, the senate still executed all of them. Take a look at the skull of (possibly) that man!
More info about the museum.
Open hours: Monday, Wednesday, Friday: 10:00 - 17:00 Saturday, Sunday: 10:00 - 18:00 Thursday: 10:00 - 21:00 Tuesday: Closed.

Pass by the old abandoned Gothic St. Nicholas Church, which looks just incredible in its ancient glory. For a few euros, you can take an elevator to the observation deck at a height of 76 meters (250 feet) and enjoy a panoramic view of the city and harbor.
Open hours: Daily: 10:00 - 17:00

Note: the bazaar is open only Sat and Sun from 10:00 till 15:00.
Here you can browse random stuff with unknown histories saved from sailors. It's a creepy yet strangely fascinating mishmash of weird things, stashed on dusty shelves! What will you take home as a memory about the trip to Hamburg?
P.S. If you're visiting Hamburg during the weekdays, as an alternative, you can have a nice walk around the Shpeicherstadt area at the harbor, which has houses in incredible Gothic Revival architecture.

It's time for lunch! Have a nice meal at a harborfront place with a terrace where you can enjoy the stunning views!
Open hours: Daily: 12:00 - 23:00

The museum walks visitors through the myriad additives, flavorings, colors, preservatives, stabilizers, sweeteners, and other substances most of us unknowingly consume with every meal. After this visit, you, probably, will read every sticker on every product.
P.S. The information presented is in German.
Open hours: Wednesday - Sunday: 11:00 - 17:00

Learn the multi-layered history of medicine! You will see medical equipment, wax models and graphics of scary diseases, and some weird stuff like the Binetarium - a piece of equipment the Nazis claimed could measure intelligence and executed people who didn’t measure up to the desired mental level.
Open hours: Wednesday, Saturday, Sunday: 13:00 - 18:00 Thu, Mon, Tue: Closed.

There was a special meal that seamen cooked in the 16th century that is called Labskaus. In Hamburg, people still love this regional specialty: it’s delicious and cures a hangover in minutes! So today you will have a typical local seaman's dinner, pirate :)
Open hours: Tuesday–Thursday: 12:00 – 23:00 Friday–Saturday: 12:00 PM – 00:00 Sunday: 10:00 – 20:00 Monday: Closed.