By now there should be a Piece of Heart in the water right in front of you.
Warp to the Witch's Hut, go a screen to the left, fall in the water, and swim up into the waterfall for lots of fairies and a Piece of Heart.
Warp to ducky drop-off #2 and talk to the Mole. Warp back to the Witch's Hut and go a screen to the left. There are 6 chests in his new cave (600 rupees)!
Now let's play the digging game! Go to the nearest Rental Shop, get a shovel, and look at the map. You'll see an X, one of these locations...
- dig in the little circle of trees to the upper left of the witch's hut.
- dig in the bottom-left of the Eastern Palace land-mass (between the bridges)
- dig in the center of the outcrop west of the witch's hut.
Dig in any of these for the final Piece of Heart.
Now go to the area with the Rental Shop south of the Eastern Palace complex. When the timer hits 18:43, Zelda will come running and (in the original format) calling for help from the north. Kill the Octoroks to save her.
HINT: walking into Zelda will stop both her and the Octoroks, so you can keep on walking into her if you want a breather to plan your strategy.
She will then follow you, so go to Hyrule Castle and she'll detach, and the old woman there gives you 300 rupees for saving her. You also get 10,000 points!
That's all for this Week, so you can go rent another shovel and dig for treasure or whatever. When the timer reaches 18:56 wait for the end of the cutscene and until the game crashes (makes funny noises).