For a traveller already near Sliema Ferries, the boat is a simple way across the harbour. It also makes a good one-way shortcut: you do not have to return by the same mode you arrived.
Read both sides of the board
The operator publishes separate Sliema and Valletta departure columns. Its winter and summer schedules differ, and Sundays and public holidays have separate service windows. Later summer sailings should never be assumed to operate in winter.
Check the Sliema–Valletta route page for the crossing and fare context. Before heading back, verify the operator’s final departure from Valletta, not the final departure from Sliema. If you are walking onward in Valletta, account for the distance from the landing to your destination.
Heading instead to the Three Cities? That is a different harbour crossing with its own timetable.