I'm sure some naitives, and naitive speakers, probably know the city better than I do, and can offer advice for thins to do outside of the convention centre. But googling the city, some obvious things spring to mind...
Miniatur Wunderland
A
model train set model planes, trains and automobiles set that fills several rooms. It's large enough to offer tours. About 20 euros each. Prebooking is strongly recomended. Backstage tours available. As are combo-tickets for a harbour boat tour.
miniatur-wunderland.de
Car museum Prototyp Museum
Classic car and racing car collection. Just under 5 euros each.
prototyp-hamburg.de
Museum Association
Website for a bunch of museums, including the City History museum, the Harbour museum, and the Work museum.
Various prices and loctions.
shmh.de
Brahms Museum
Dedicated of course to Johannes Brahms, and probably worth a visit by anyone interested in music. 9 euros each.
https://brahms-hamburg.de/Can anyone from the area recomend anywhere else of interest, or any good local eateries in the vacinity of the CCH?