There was one place I dreamed of visiting for a long long time...the mudflats on Okoshiki Beach in Uto city, Kumamoto.
This mudflat is most clearly seen during the spring tide when the tidal range is the greatest. The beautiful regular pattern of the mudflat stretching offshore is a sight to behold. However, to create this scenery you definitely need a beautiful sunset in the background.
The other must-see spot is the 'Nagabeta Kaisho Road' nearby. At this beach, the spring tide rises as much as four meters. Naturally, ships can't sail out at low tide. The causeway was built to reach ships anchored off the coast by car, and designed to be completely submerged at high tide. Street lights illuminate the underwater road, and the only thing visible is the brightly-lit water surface...what a magical sight!