In the golden circle, there is always Fridheimar. It is fine, but can be hard to get reservations. My personal favorite in the GC is Mika, which happens to be extremely close to Fridheimar. They have a pretty big menu, and are known for their pizza. I have never ordered that as the lamb always wins out for me, but it looked really good! At Gullfoss, their cafe has great lamb soup. My husband says that is a must on almost every trip, lol.
Most lagoons have bistro's on site such as Fontana, Secret Lagoon, Hvammsvik (very good!). You can stop and eat without having to do the lagoon itself.
Along the south coast, at Jokulsarlon there are food trucks. We have had fish n chips there that were very good.
In Hvolsvollur, the Eldsto Cafe is great. Right by it is a local product store, which is a nice stop.
In Vik, Black Crust Pizza and The Soup Company are both very good. Black Crust does take out as well. There is also Skool Beans which is a converted school bus which also has bagels and pastries. Their hot chocolate is really good!
There is nothing near the ferry, unless you count the little kiosk thing at Seljalandsfoss.
In Selfoss at the main roundabout, is a hot dog place. It has a drive through or you can order inside, but no seating. It has the most extennsive hot dog menu you can imagine. Very good! If you are coming from Reykjavik, at the main roundtable there in Selfoss take the first exit out and then the first driveway into the little shopping center and you can't miss it.
The gas stations often have grills where you can order and sit and eat, but they also have pre made sandwiches that are great in a pinch. The grills have been quite good the times we have stopped.
You can also hit Bonus/Netto/Kronan and get premade soups etc and take those back to your cottages to heat up.
