Detect astrophysical sources of high energy neutrinos.
Water serves as target, detecting medium, and shielding.
Use a large array of phototubes to detect Cerenkov light emitted by muons in water - reconstruct track direction. Deep water filters out ordinary cosmic radiation background from above. Need very deep, very clear water, close to shore laboratory. Hawaii offers ideal site off Keahole Point on Big Island. Remote long-term operation requires high reliability.