Both tent camping and RV/Trailer camping. A few Yurts to rent also which are somewhat isolated from the other camping areas. Reservations can be made exactly 6 months in advance and only a few sites are kept open for walk ins anymore. The sites along the cliff overlooking the lake have fabulous views but are ONLY for tents and one should NOT camp there with small kids.

The RV camp sites and many of the other camp sites are inland from the cliff and while wooded are generally very close together and most do NOT have a lake view. The ONLY quiet areas in the campgrounds on the weekends are the cliff tent areas since it is a party island and the young people camping in the interior areas seem to never go to bed.  

The Park has a rocky beach (shoes NECESSARY) which is actually a nice swimming area if you aren't looking for sand under your feet or blanket.  That beach is the only free public place to swim on the island (some hotels do have pools). That beach area is a great area though to launch a kayak or sailboard to use in the cove. There is also a regular boat ramp for larger boats or jet skis.  NO overnight boat tie ups at this state park dock (some at the downtown state park, but those are hard to snag)

The town is about 1.5 miles down the road and easy to get to via bicycle or island taxi - vehicle parking very limited if you try to drive into town. and the town has numerous bars and restaurants with lots of live entertainment on the weekends. 

The town is definitely a"party" location on the weekends during the summer months. and there is a very pretty and active harbor there, usually with 100 to 200 boats including some in the 40 to 50 foot range in the harbor on the weekends. 

The slow ferry to the island (Miller) is the car ferry and it has free parking if you can leave your vehicle behind on the mainland and transport your stuff to the campgrounds via a bike trailer or some other way (about a mile+ from the ferry dock to the state park). If you do take your vehicle over note that the wait time to bring it back on a Sunday while usually 2 to 3 hours can also be up to 6 hours from when you get in line (beware the Miller ferry stops running about 8pm, ie: near sunset). Usually little or no wait time when bringing a vehicle or RV back mid week.

Pick when you want to go depending upon how much you enjoy noise and partying.  Mid week during the summer season is the best time for those who aren't into 24 hour partying and weren't able to snag a cliff side camp site.  Kelly's Island is quieter and has a nice natural sand beach, so better for weekend trips if going with a family, or if you definitely need a sand beach.  If bands, noise, drinking, and people watching are your desire, well this is the place to go on a summer weekend (ala Key West party atmosphere)