Rocky island is a good launching point out to devil's island. If you can, get site number 1. It's out on a beautiful sandy beach. Site 2 is difficult to access. There's no sandy beach and you need to struggle up a steep hill with your gear. Site 3 is in the grey area in between. There's a decent tail to an overlook on the northwest side of the island. A bench to sit on and a view of devil's island in the distance. But I recommend a trail not on the park map. Take the trail past the ranger station, past the group campsite, through the private property (be a good northlander: be polite, say hi and don't mess with anyone's stuff) and down the sandy beach until you reach a large stump protruding from the beach. The trail is on the left and easy to miss. Brings you to a gorgeous beach you could spend the whole day on.
We sailed up from Washburn to Rocky. We started late so we ended up coming in around 1:00 am in the morning. We were able to see the dock just fine with flashlights so docking wasn't a problem. It's a very large dock allowing for tons of room for multiple vessels. Throughout our stay I would say I saw 5 large boats on the dock at once. There are 5 campsites near that dock. Site 5 and 4 are very close to the dock and in my opinion the best sites on the island. The picnic bench on site 5 has LTE service. These two Sites also have access to very clean porta-potties. Sites number 3, 2, and 1 are a large walk from the dock. Great for people who are kayaking because they're right off the beach and easy to access. They have access to latrines that resemble ones I've seen in the boundary waters. Overall our trip was a blast!
The volunteers while we were there were the best 7/27 to 8/10 friendly and helpful. Cleanest outhouses ever