We have a rental car booked for our entire trip of 15 days , since Hydra doesnt allow cars , is it possible to stay at Paros overnight and take a ferry ( online it says there are 30 minute ferries to hydra) to hydra for the day and be back to paros for the night ? is that possible ? Would one day in hydra be sufficient to cover hydra ?. Should all ferries be booked in advance ? what websites should I look into to do the same ?