As anywhere else, much depends on the choice of restaurant and items on its menu. Also, it is worth asking around among other travellers within your location and/or guests at the hotel. Local people will also be of help, including at information centres. Note that the Icelandic currency is not internationally convertible so if you find you have kronur left over at the end of your stay it is strongly advisable to exchange them back for the currency of your choice before leaving - there is a bank at the airport and it is open at all times when flights are arriving/leaving.