There will be 7 of us traveling amongst Capri, Positano and Salerno at the end of June. Is it necessary for us to purchase our ferry tickets in advance, or just day of at the dock? The ferry website advises to buy now in order to ensure a seat since that is a busy time of year. But we really aren’t sure of which ferries we will be wanting to catch at this time. And we don’t know how many bags we will have that will incur the additional surcharge.