Cargo ship travel agencies

Name	Link
Kapitän Zylmann GmbH	https://www.zylmann.de/en/start/welcome.html
Internationale Frachtschiffreisen Pfeiffer GmbH	https://frachtschiffreisen-pfeiffer.de/en/
Hamburg Süd Reiseagentur GmbH	https://www.hamburgsued-frachtschiffreisen.de/
Globoship - Frachtschifreisen	https://www.globoship.ch/frachtschiffreisen/

It is best to book well in advance as passenger cabins on cargo ships are limited and the most popular routes sell out quickly. Plan six months in advance to ensure the desired trip.
Be aware of the sometimes quite high cancellation fees!