Generators....

[SimonH2]

Yes, totally unique, and quite intriguing ...

Ah, the "totally" as opposed to "only partially" unique discussion
But yes, water is a very amazing substance. You only need to look at it's phase diagram to see that it's not like anything else we know of with a similar molecular mass. And as Eddi points out :

I think the bit about life on earth, pertains to the fact that ice is less dense than water, if it weren't then obviously it would sink and not offer any insulation leading to more and more freezing, therefore in ice ages the oceans would have frozen solid, instead of staying liquid underneath.

Not just the oceans, and not just ice. Water starts to expand below about 4˚C, so not only does the ice float, but water colder than 4˚C will rise above the warmer water - so leaving the water in the bottom of lakes etc a few degrees above freezing.

The phase diagram in the page I've linked to above is a clickable map - there are some very interesting pages there.

 

[EddieM]

Also has the same RI as diamond. Though that's more coincidence than an amazing property, which are down to the oxygen's SP3 (or is it SP2, forgotten!) electron orbital hybridization.