Isle of Armor Diglett locations: Stepping-Stone Sea
The Stepping-Stone Sea is one of the larger areas but only has seven Diglett to find, since most of the area is water.
Enter Stepping-Stone Sea from Loop Lagoon and the first, elongated island in front of you will have the first Diglett in the narrow section.
Go to the smaller, circular island to the south and you'll find two Diglett (a Dugduo?) next to each other by the rock.
Now go further south, past the larger inaccessible rocks, to the island behind them. The first Diglett is in this corner, next to the TR item.
Go through the tall grass round to the left now and there's a Diglett by the edge.
Then double back on yourself and go to the only section of the island you haven't been to yet, which has this Diglett by the berry tree and some flowers.
The final Stepping-Stone Sea Diglett is on the other side of the big tree.