From the mainland there are a number of ways you can reach the Isle of Wight.
Travel from Southampton via Red Funnel by car ferry to East Cowes. Ventnor is approximately a 40 minute drive from East Cowes.
Wightlink have car ferries which go from Portsmouth to Fishbourne (40 minute drive to Ventnor/Shanklin) or Lymington to Yarmouth (50 minute drive to Ventnor).
Train travel from the Mainland can be booked straight through to Shanklin station, including your foot passenger ferry through Ryde Pierhead. From Shanklin station, Ventnor can be reached by bus or taxi in 10/15 minutes.