by getting the northwestern sea chart and going through the rocks in a spcifec order that is shown on a map in a seceret hideout on molina island
In Link and the legend of Zelda, Phantom Hourglass, you get the hammer in the isle of ruins, or the island of the dead.
it is on eddo's island
At the Goron island dungeon
youtube: legend of zelda phantom hourglass by cesaritox09
the fourth
you get it in the temple of courage at modlia island
in the ice temple on frozen island
In the temple
boomarange
go to gust island
In the temple on Goron Island
You can get the bow from the Temple of Courage on Molida Island.