Board a standard picket boat for a traditional caldera tour, discontinue for swims, stopover at the volcano
https://www.scribd.com/document/994129440/Private-Santorini-Tours-for-Small-Groups-Customized-and-Crowd-Free-199515
Board a average wooden boat for a conventional caldera travel, end for swims, stopover at the volcano, and enjoy onboard thoughts and snacks.