Underwater pub. It's just a usual pub, really, but every Tuesday and Thursday it has an opera night! That basically means that between around 9pm and 11pm there are professional opera singers performing in front of the visitors at this small cozy pub. There are 4 acts, each consists of 3 singers perform a short piece from more or less known operas. Feel free to come late - it's a very casual atmosphere, and there are plenty of breaks for chatting, but while they are singing make sure you don't whisper a word! It's certainly one of the more unusual things to do in Oslo, and as you might guess, some of the singers may be gay and up for a drink afterwards!