I worked on the SNO+ experiment for grad school and actually got to go in a boat in the ultra pure water surrounding the acrylic vessel to search for leaks. It

I worked on the SNO+ experiment for grad school and actually got to go in a boat in the ultra pure water surrounding the acrylic vessel to search for leaks. It is an impressive piece of engineering to construct such a detector requiring a lot of money and effort. They actually had to bring down the acrylic vessel in pieces because the whole thing wouldn't fit down the mine shaft elevator. Then they glued them all together underground (this is no small feat since the acrylic vessel has to be optically clear for the photons to travel through to the photomultiplier tubes).