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

Not at the pole - the ice is essentially transparent, they made a 3d grid of detectors by melting deep holes in a grid and dropped strings of detectors that then froze in place