The busiest time of the week for travel from Thera to Kos by ferry is at 12:00 a.m. on Tuesday. When planning to travel around this time, tickets should be booked well in advance as they may sell out. Around 4:00 a.m. on Thursday is when the fewest number of ferry tickets are sold. If you’re looking for a little extra space, the ferry departing at this time is the least likely to be crowded.