William with a bit more re: Kumamoto water. Takamori, a town in the southeast corner of Aso caldera (inasmuch as a round caldera can have a corner) is famous for its tunnel-to-nowhere. In 1973, work on the Kyushu-Chubu Crossing Railway, which would have connected Kumamoto with Oita, was begun on what is now the Minamiaso Tetsudo Takamorisen (南阿蘇鉄道高森線), which entailed digging a tunnel from the caldera floor to emerge somewhere around Takachiho. Things bogged down in 1975, when water began spouting out from tunnel walls in volume increasing as the tunnel progressed, and in 1980, with 2055m dug, the project was abandoned. The tunnel continues to spout pure spring water of 32 tons per minute, and its first kilometer, known as Takamori Yusui Tunnel Park (高森湧水トンネル公園), is open to visitors. Narrow lanes on either side of the waterflow pass through the dimly-lit tunnel, with strobe lights causing streams of water droplets cascading from the walls to appear like strings of pearls. Its 17°C year-round temperature make it cool in summer and, ironically, warm in winter. Several events are held to celebrate seasons, particularly Tanabata and Christmas. In July, colorful Tanabata decorations are hung the length of the tunnel, enhancing its sense of mystery. Below photos nabbed from the Web: tunnel entrance; water droplets under strobe lights; Tanabata decorations; tunnel end. Also, while swimming in the stream outside the entrance may be discouraged, as in the final photo, bring your trunks just in case. Access easily by train; change lines at Tateno Station to the Minami-Aso railroad and disembark at its terminal, Takamori station. The tunnel is a short walk from there. An English-language welcome: http://takaramori.com/en/spot/leisure_detail.cgi?up_spofo1=1005