You don’t have to waste a day on the ship to get there. Kea is just an hour and a half by boat from the port of Lavrio just outside Athens.
While the island has seen an increase in visitors in recent years, the largest percentage of summer visitors are Greeks and not foreigners, which ensures a less touristy feel. Bring (or rent) a bike. There is no better way to see this island, which has 65 klm. of cycling routes.