Diagonal Clues

Easy Used by Smart Hint

Two clues that touch only at a corner can never share a cell — the two squares between them are sea.

Sea
Cells that establish the pattern
Where the conclusion lands

How it works

These two clues touch only at a corner — their islands can never share a cell.
The two squares between them, each orthogonally touching both clues, can't belong to either island without connecting them — both are sea.