Zelda The Phantom Hourglass - I am trying to get the NE sea Map

Hi Guys

Can you help, I am in the Sea King Temple (again for the 3rd Time) and I have not much sand left in my hourglass it takes me all the sand i have to get through to the 8th level then I die.

Is there anyway I can go back and start again to try and get more time. I have tried to start the dungeon again but i can't get passed the sun door it wants me to press the sun symbol on it and when I go back to the sea chart to press the sun symbol it's gone.

Please help.