Water and ice versions exist, IceCube consists of detectors dug into ice and Super Kamiokande (example) is a big container of ultrapure water (not heavy). Hyper Kamiokande will be even bigger.
https://en.wikipedia.org/wiki/IceCube_Neutrino_Observatory https://en.wikipedia.org/wiki/Super-Kamiokande https://en.wikipedia.org/wiki/Hyper-Kamiokande