Expedition yachts have undergone a radical transformation over the last decade. The first supersize explorers were often supply vessels or commercial freighters that had been converted—often compromising comfort—into bare-bones, long-distance cruisers. These days, the modern explorer yacht has evolved into a go-anywhere vessel designed to reach the outer limits, with all the comforts and space of other superyachts.

The new Sanlorenzo 460EXP, which will debut at this year’s Monaco Yacht Show, is a great exam…