One of the national parks on the northwestern coast is Snowdonia, home of some of Britain’s most spectacular scenery and the tallest mountain in Wales, 3,560-foot Mount Snowdon. Legend has it that King Arthur had a duel here with an ogre. Arthur won, whereupon he buried his foe at the summit. Snowdonia also has Llyn Tegid, the largest natural lake in Wales, and plenty of picturesque towns such as Betws y Coed and Beddgelert. See the area best by hiking, biking, and kayaking.
In the center of the country is 500 square mile Brecon Beacons National Park, established in 1957. A couple on a honeymoon could easily spend the day hiking through mountain passes (look out for wild Welsh ponies and sheep along the hillsides and meadows), woodlands, waterfalls, and caves. There are also medieval castles and churches such as Llanthony Abbey, where portions date back to 1108.
The third national park is Pembrokeshire Coast, Wales’ only coastal national park. It boasts sandy beaches such as Barafundle Bay and Broad Haven South, towering rugged cliffs, and hidden coves. After a day swimming, unwind in a seafront restaurant with a bowl of mussels and a nice bottle of white wine; you might spot a dolphin frolicking offshore.