Getting to South Kitsap via Ferry is a great experience. There are four ferry routes that lead to Kitsap County from the East side of Puget Sound.
The quickest ferry ride to South Kitsap is via the Fauntleroy- Southworth Ferry. It is about a 30-minute crossing with a quick stop at Vashon Island.
The most scenic, and longest route, is from downtown Seattle to downtown Bremerton. If you are driving onto the ferry in Seattle, you can exit the ferry and take a short 20-minute drive to downtown Port Orchard. If you are traveling on foot or bicycle, once you get off the Ferry, you can catch the Foot Ferry from downtown Bremerton, directly to downtown Port Orchard. This route also gives you a great view of the Puget Sound Naval Shipyard from the water side.
Two other routes will get you to Kitsap County from further up the Kitsap Peninsula. There is a ferry from downtown Seattle to downtown Winslow on Bainbridge Island. From there it is about an hour to Port Orchard. There is also a short ferry trip from downtown Edmonds to Kingston at the northern end of Kitsap County. It takes about 45 minutes to get to Port Orchard from Kingston.
Each route is a great trip- give them all a shot! Here is information on Ferry Schedules.