We are gonna have fun now!!

Here's the game and the rules :
Game : TREASURE HUNT
Rules: A long long time ago in a speck of dust nearby ( lol ) The magic puppy, Bluno or
w/e got lost... he is trapped in this speck of dust, only figuring out this riddle will
unlock him. ( the winner gets a bluno puppy :P )
Carol is travelling by ship from south of the equator to the north.
She has a nice little second class cabin which has a bathroom, but no window.
Carol has no compass nor other instruments. 
 Yet, without leaving her room or talking with anyone, Carol knew exactly when the ship
crossed the equator. 

How did she know? 
Hint: it has to do with water

Because...of...how hot it was? :D'
+Lost.+

Hmmmmm i'm guessing it has to do with.....nvm prolly not

oook nother hint : Sink

They were sinking a bit because the water was less dense...?  T___T;
I'm guessing.  ;__;

lol ok i'll give u the bluno cus of your efforts, oresama. the bluno will have the answer
revealed :P

Ooooh!  xD
I didn't know that!  o___o;;
Well, actually, I did, but I forgot that.  T_____T;;
I was told that in grade six, and then told that again earlier this year (grade eight),
but I didn't remember it at all. xD
Thank you, though~.  :D

hehe no problem ^-^ Bitter didn't need it cus he's my brother :P

He is~?  o:
I never knew that.  >_>
I have a brother, too; he's younger than me (he's in grade four).  o_o