There are several different companies operating between Büsum and Helgoland (not to mention the many other costal cities of having ships going to Helgoland).
We took the MS Lady of Büsum wich is a comparatively quick ferry. The 50 km trip from Büsum to Helgoland took about 1 hour and 45 min.
The ferry goes to Helgoland in the morning and returns in the afternoon giving people about 4-5 hours of sightseeing on the island.
Prices are about €30 for a return ticket (2006 prices).
Probably you might have problems to find info about getting to Helgoland in English in advance. At least I didn't find anything on the net (if you find something let me know).
So to get infos, try the following email:'email@example.com'.
It is the email of the company running the ships between the coast and the island. I guess they can help you.
Of course you can get information directly at the ticketseller!!!
Helogoland can only be reached by boat. The trip is - on a sunny day - of great pleasure. The waves beneath you, the wind and sunshine ... everything a sailor needs (-:
The shortest cruise one can do from Cuxhaven and leaves early in the morning to go back in the afternoon. The rock has not that big harbour (only for sailingboats / yaughts) and so the ship stays out of it. With small boats one is put ashore.
Check the Online Map, which might help you to plan your trip.
Different languages available, by clicking on the small flags.
It's not just fun to travel to Helgoland by boat. It's the only way. (O.K. you could swim the ca. 70 km...)
We took a catamaran boat with a higher speed than a normal boat.