Gosh, you're right. The reason that water expands when it freezes must be an utter mystery to science.
http://www.iapws.org/faq1/freeze.htm
Then again... :-)
That is why ice floats on water, for which we should all be thankful because if water behaved "normally" many bodies of water would freeze solid in the winter, killing all the life within them.
Thankful? Thankful to whom? Who set the laws of nature so that water freezes and expands so the fish don't die each winter?
If water behaved "normally" (i.e. if water did what logic tells us it should when it freezes and contracts instead of expands). Not one of us on earth is powerful enough to invent this natural law or to invent this exception to the law - precisely my point.
Science may try to explain the exception but it can't change it nor explain where the wisdom came from to create this exception. Atheists try to use science to "prove" God doesn't exist and, in their folly, they actually produce more evidence that there is a cosmic intelligence that so structured the world to allow fish to survive winter.