Go with Scanbalt Experience from your hometown for the International Student Cruise (ISC). With this package you get the same cruise as everyone else but you will also have a convenient bus trip from your hometown to the ferry terminal in Stockholm and home again.

Departure: April 16th, in the moning (you see exact hours if you click on the departures below)
Price: Depending on which tour see departures below
From: Umeå, Borås, Trollhättan, Göteborg, Sundsvall 

Included: Bus transport to the ferry terminal in Stockholm and return, place in a cabin, guided tour in Riga, one buffet on the boat first night (including beer and wine!)

Here is a movie to an earlier ISC to Riga!

 http://www.youtube.com/watch?v=YFevvly2jw8&feature=youtu.be

 

Package Holiday