Santorini is a huge problem, even with fewer ships than that. Getting up the hill was not mentioned by the previous poster. The line is formidable to get up but years ago we did find a way around that which I’ll explain in a minute. We found no good option for back down. We tried walking down once, but never again, two of our group slipped and landed in donkey poop.
Back to our arrival after getting off the tender. We saw numerous small boats offering to take us to the other end of the island. Some offered a mini tour which included a bus ride up the hill at that end by Oia which is my favorite part of Santorini, and a bus ride back to the town where the cruise ship is. Worked out perfect and we just took a local bus back to town, less than a dollar at the time and really scenic. Still couldn’t avoid the huge wait for the lift down. If there are no tour offerings with a bus ride you can walk up the road at the far end of the island.