Use the shovel. You get it on Molidia Island inside the Wayfarers cave.
you have to dig near a tree on molida island
dig a hole in front of a coconut tree and jump in
u dig by the clostest palm tree near the cave
You can dig in Phantom Hourglass by equipping the shovel and tapping the place that you want to dig with your stylus.
it is on the game first you need the shovel then you have to dig a hole below a tree.
there are palm trees on the top of the island (excludes cave) dig under them
u dig just under the tree by the fishermans house [left of the house]
On Zauzz Island in "The Legend of Zelda: Phantom Hourglass," you can dig in the area marked by a large X on your map. This location is typically near the center of the island, where you can uncover treasure or useful items. Be sure to use your shovel to dig in that specific spot to find what you’re looking for.
go to gamefaq.com dig under a tree near the guys house
in front of the second tree from the mailbox on molida island.
go to molida island and dig in front of the palm tree. and hit all the statues
get a salvage arm and go get the sun key then go to molida island and dig in front of a palm tree