The islands are virtually uninhabited except for a few Park Service Rangers and campers (mostly Santa Cruz). For day tripping, bring your own lunch & drinks. There are no concessions on the islands. On the afternoon run back to the mainland, a couple of the Island Packers boats do have grilles and sell burgers, snack, drinks & beer.
AH... cookin' in the great outdoors... no restaurants here unless you count yourself. here is a suggestion and I believe a darn good one... don't plan complicated meals. you have to carry everything in and out of the island, so try to make it as simple as possible...we brought stuff like spaghetti, and velveeta mac and cheese (just need water to cook) or if you want it even more simple... peanut butter and jelly sandwiches, granola bars, trail mix. l
In the pic, the two heroines after cookin' their famous mac and cheese... a hit all around!