This 1kton water tank was to be used to house the 1kton water Cherenkov detector installed as part of the near detector complex. It was originally used for a beam test with charged particles to test the performance of a water Cherenkov detector in 1994. For the K2K project it was slightly modified to meet all the requirements as part of the near detector. The height is about 12m and the radius is 5.4 m. After this photo was taken and the experimental hall labelled as "Front detector" in the photo was excavated and prepared for the experiment, this tank was moved to the hall and all the structures and equipments were installed inside.