Why do you do this to me, Ancient Greek?

Why is harbour masculine, when 'earth', 'sea' and 'ship' are all feminine? Why does 'lifeboat' bear no resemblance to 'boat'? Why is there a specific word for 'to pour libations' that bears an uncanny resemblance to the verb 'to run'? Why is there no way other than context to determine if a word is 'I enslave' or 'I am enslaved'? What on earth is meant to be the difference in pronunciation between Pi and Phi? Why does Zeus become 'Dia' when it goes into the accusative? What the hell is wrong with the third declension?

And why did I leave it this late to start revising my vocabulary for the final exam? *sigh*