You'll get a mission where you have to go get a thing called the frozen tears 
dont ask me how to complete this yet because i'm not sure yet but still all you 
do is climb up at an angle and slowly make your way up the mountain surrounding 
you and jump off but kind of slide down the side of the hill and youll be able 
to swim in the water around it and look around yeah not alot to do down there 
but it is fun to do oh and if your wondering if you'll fall off and have to load 
your game back and start all over again there is only one way i've found to get 
back up and its hard jump and swing your sword at the right time and a glitch 
will happen and you'll float in mid-air til u jump again then just swing your 
sword and repeat til you make it to the top again.