From Gulf Shores there are two ways to reach Dauphin Island, and they are not comparable.
By ferry: drive west along the Fort Morgan peninsula to the terminal at the end, roughly forty-five minutes from Gulf Shores, and cross the mouth of Mobile Bay. The crossing itself is part of the appeal, with the fort behind you, ships moving in the channel and dolphins in the wake more often than not.
By road: north out of Gulf Shores, around the top of Mobile Bay, through Mobile, then south for the better part of thirty miles on Alabama 193 across the Gordon Persons Bridge. Budget two hours each way.
The ferry runs year-round on seasonal schedules, takes vehicles and foot passengers, and suspends service in strong winds or heavy seas, with figures around thirty-five miles an hour of wind or six feet of sea commonly cited. It also closes for some public holidays, and there have been longer interruptions. None of that is unusual for a small vehicle ferry. All of it means the same thing: confirm it is running, and confirm the day's timetable, before you leave.
Arrive early for a vehicle crossing in summer. Sailings fill and there is no standby guarantee.