Isle of Armor Diglett locations: Warm-Up Tunnel
Since it's such a small area, Warm-Up Tunnel has just three Diglett to find.
As you enter from the Training Lowlands side, the first Diglett is immediately on your left.
The second one is behind the pair of rocks, next to the junction.
The third and final Diglett is on the right-hand side as you exit the tunnel.