Web alarm clock for 3:12 a.m.
You are wrapping up for the night and heading out to meet the night ferry at the pier, so a 3:12 am alarm gives you a clear point to stop what you are doing and leave. It also leaves enough room before 4:00 am to pick up your bag, check the ferry details, and reach the waterfront without turning the departure into a rush.
Your ferry plan can be interrupted if the alarm page slips into the background while you check messages, transport updates, or a map. Keep the browser available and confirm that its sound is allowed after switching back to it. A background page may be slowed or silenced by the browser, and the night ferry alarm will not sound if you close the page or let your phone sleep. Use a separate phone alarm as backup when missing the sailing would leave you at the pier.
Before you finish packing, arrange the light you will use when the alarm sounds. At 3:12 am, a bright ceiling lamp can feel abrupt, while a dim lamp near your bag lets you find keys, footwear, and identification without searching in darkness. Set that light within easy reach, and leave the path to the door clear for a quiet departure.