Avoid the tourist boat-tours with set itineraries, during which you cannot determine your own pace and opt instead for a private tour. If you are in a group, it will not likely cost that much more and will most certainly be more enjoyable. The best companies on the island are Santorini Yachting Club and Sunset Oia. We did try a third company, but had a few mishaps, so we recommend you stick to one of these two. Request that they take you to Red Beach, which looks absolutely stunning from the sea, and ask for stops along the way so that you can take a dive, should the water temperatures be pleasant during your visit. Another beach to which sailors like to take tourists is White Beach, which is pretty if conventional. How do you like the idea of swimming near a volcano crater? Opportunities like this do not present themselves all the time. Please note that the water is quite warm, reaching 32C/90F, brownish and has a lot of sulfur. Take an old bathing suit as the sulfur odor will not come off, yet you may want to keep if as a souvenir of Santorini. Ask the sailor to take you to the island across from the volcano, Thirassia. You’ll find mansions and yachts around the beaches accessible only by boat. Take advantage of the private tour and do what you enjoy more, be it a busy trendy beach or a tranquil secluded one. After all, you are the captain!