According to Wikipedia, Hamburg has more bridges than any city and more canals than Amsterdam and Venice combined. All this and Europe's 2nd largest port (behind Rotterdam) make Hamburg one of earth's most nautical places.
Strolling around the old city and crossing many of these bridges along historic canals, I've found two specialist bookstores devoted entirely to nautical topics.
|translates to "Nautical Charts Nautical Books"|
|translates to "Fox's Ship Bookstore"|
Yours in supporting local bookstores,