For food & drink, Catamaran Caldera Cruise delivers.
Widely rated the best single splurge on the island: you see Santorini's coast as it's meant to be seen, swim in spots you can't easily reach by land, eat well, and end on a sunset over the water with a drink in hand. The catch is the price and that 'semi-private' tours still pack a dozen-plus strangers aboard. For couples and groups, consistently worth it.