Regardless of whether it's England, Wales, Scotland or Northern Ireland—each a distinctive and proud entity—both pastoral countrysides and metropolises in these regions are steeped in history and cultural traditions. One only needs to conjure thoughts of Stonehenge, Westminster Abbey or a cozy country pub to recognize the significance of its remarkable past. But the U.K. is also intrinsically modern and takes great pride in its cutting-edge innovations, whether they're in art, fashion or technology.

While many large-class cruise lines are making their way to this region, it is best explored on smaller vessels and river cruising expeditions. The entire European market has begun to attract more attention from big ship operators, but continues to be the mainstay of smaller, more luxury- and deluxe-class lines.