No, you do not need a passport to travel on a ferry to the Isle of Wight from mainland England (ports like Southampton, Portsmouth, or Lymington). Because the Isle of Wight is part of the United Kingdom and the journey does not cross an international border, there is no passport control or immigration check. British citizens and residents can travel freely using the ferry services operated by Wightlink, Red Funnel, or Hovertravel. While a passport isn't required for travel, it is always a "good practice" to carry some form of photo identification, such as a driving license, especially if you have booked a discounted senior or student fare that requires age verification. International tourists should also carry a copy of their ID just in case, but for the vast majority of travelers, a ferry to the Island is treated exactly like a domestic bus or train journey. You can simply turn up with your ticket (or buy one at the terminal) and board the vessel without ever reaching for your passport.