My wife and I were lucky to travel with Kathrin on a 6-hour customised first impression tour. I found her through Trip Advisor and sent her my basic requests. Our interest was to explore some hidden spots (with few people) for good photos. She responded very quickly with a thoughtful plan.
Kathrin is a gentle and knowledgable guide. On the day, she drove us around the island and showed us many places including some famous tourism spots as well as some hidden places but with either interesting stories or amazing views. We were also told about the history, geography, biology, and lots of interesting aspects of the island. You would not never get bored during the trip. We were also offered a good wine-tasting activity at the end of it.
We are very satisfied with her trip plan and we really enjoyed the whole day. She's definitely a expert of Santorini and I would highly recommend my friends to travel with her in the island.