A really nice town about 50 minutes drive from Gothenburg is Varberg which is just by the sea.
You can also go by train of course. www.sj.se
They have fantastic beaches, a fort, and is a very cute town to visit.
They also not less than two spas to visit; Varbergs kusthotell and Asia Spa

http://www.varbergskusthotell.se/spa/
http://www.varbergsstadshotell.com/

 

http://visitor.marknadvarberg.se/

Apelviken
Foto: Mikael Pilstrand