JRP - Based on info from people I know who have been to Santorini in the last 2 yrs, they have improved the anchoring / mooring there.......I'm a little fuzzy on details but they seemed happy about being there. Here's a link I just found
Santorini island maps - Sailing holidays, cruises and yacht charters in Santorini
Edsml: Which reminds me I left out one suggestion = The Greek Waters Pilot......well worth the $$$, if you do not have already.
Amazon.com: Greek Waters Pilot 10th Edition: Rod Heikell, Imray, Laurie, Norie & Wilson Ltd: Books