Ryusendo Cave

Come for the water. Ryusendo is a limestone cave in the hills of Iwaizumi, and about 700 meters of it are open, a damp, echoing walk past flowstone to three lit underground lakes. The first is 35 meters deep, the second 38, and the third 98, and the water is so clear you look straight down into a blue that seems to have no floor. A fourth lake, closed to visitors, has been measured at 120 meters. Inside it stays around 10°C all year, so bring a layer even in August. The loop takes roughly 40 minutes and ends with a climb of more than 200 steps from the third lake. Admission is 1,100 yen, including the small Ryusen Shindo science museum across the road. It is a long way from anywhere. From Morioka it is about two hours by road, and the direct JR Bus Tohoku service runs only four times a day, so a day trip leaves little room for a missed bus.