Phillip Island is easily accessible by bridge from the mainland and is only 1 1/2 hours drive from Melbourne, Victoria.
From Melbourne Airport take the Tullamarine Freeway to City Link. Turn off at Monash Freeway and onto the South Gippsland Highway which eventually feeds into Bass Highway. The Bridge is accessed from San Remo, the last land fall before you head over to Phillip Island. Stay on the main Phillip Island Tourist Road leading to Cowes township until you enter onto Thompson Avenue, the main street of Cowes. Follow this until you reach the end and turn right at The Esplanade. Follow the sea-front to the very end - this is Erehwon Point then turn into Steele Street. The Castle is on the left-hand side.
The only public transport available is a V-Line Bus which leaves from the Spencer Street Railway Station in Melbourne.