Nineties grunge and nu metal, loud but never crushing.
When Pinguin Radio began giving particular sounds their own streams, the louder end of its collection needed somewhere to go that was not quite the metal channel. On the Rocks became that place, meant in the station's own words for hard rock that is not too heavy, with Aardschok next door for anything that is. Like every Pinguin stream it is looked after by one of the foundation's genre specialists, and it was already part of the family by June 2017, when a technical crash briefly knocked it off air along with two sister channels.
Nineties alternative rock carries most of it, the grunge bands and their post-grunge heirs, with the heavier alternative-metal and nu-metal records of the same years close behind. Pop punk and skate punk turn up a lot as well, newer riff bands keep it from turning into a museum, and Dutch and Belgian rock acts get a regular look-in between the big American names.
Volume up, eyeliner optional.